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Audit Complete

Results for https://bris.ac.uk

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GB · GBP (£) · Estimated Applicable regulations: UK GDPR · PECR · Equality Act 2010 Dev cost: £75/hr How jurisdiction is detected
Brazil Brazil · Sao Paulo Completed: Apr 22, 2026 20:58 UTC
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Mobile 375 × 812

Screenshot of the audited page (Mobile 375×812)

Desktop 1440 × 900

Screenshot of the audited page (Desktop 1440×900)
C70

Site Health

Score: 70 / 100

Based on 8 categories, 0 sections

Decent speed, but optimizing further could improve engagement.

Good foundation, but a few gaps could be exploited.

Several issues make your site difficult for assistive technology users.

Solid SEO basics — a few optimizations could boost rankings.

Good server performance with room for optimization.

Several regulatory requirements are not yet met.

Missing metadata means poor previews on social media and search.

Heavier than average — reducing page weight saves energy and bandwidth.

How is this calculated?

The overall score is a weighted average of individual category scores. Categories with more impact on user experience and security carry more weight.

Performance 25%Security 25%Accessibility 15%SEO 10%Infrastructure 10%Compliance 8%Content 5%Sustainability 2%

Weights reflect general web best practices. Individual needs may differ.

How the composite score is calculated

How you compare

Apple · 1113 peers
You 70
·
Avg 73
At average
0 50 100
Better than 13% of Apple sites See full Apple benchmark →
Microsoft 365 · 2090 peers
You 70
·
Avg 72
At average
0 50 100
Better than 15% of Microsoft 365 sites See full Microsoft 365 benchmark →

Top Priorities (5)

1

Content-Security-Policy header is missing

Security gaps expose your site and users to attacks, eroding trust.

Security › Security Headers
2

HSTS header is missing

Security gaps expose your site and users to attacks, eroding trust.

Security › Security Headers
3

No Content-Security-Policy header found

Security gaps expose your site and users to attacks, eroding trust.

Security › Content Security Policy
4

Page weighs 5.9 MB (4.0 MB transferred)

Performance issues directly impact user engagement and conversion rates.

Performance › Page Weight Budget
5

59 third-party resources (100% of weight)

Performance issues directly impact user engagement and conversion rates.

Performance › Page Weight Inventory
View fix priority matrix

Fix Priority Matrix

5 findings

Quick Wins

3

High impact, low effort — start here.

Strategic

2

High impact, requires investment.

Easy Improvements

0

Small gains, minimal effort.

Nothing in this quadrant — good news.

Deprioritize

0

Low impact, high effort — do last.

Nothing in this quadrant — good news.

← Low effort High effort →
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What fixing these means

Your site performs reasonably well, but a few targeted fixes could meaningfully improve results. Your LCP of 24.7s exceeds Google's 2.5s 'Good' threshold and the 2 performance issues below directly contribute to it. Addressing the critical issues below would have the most immediate impact on your user trust.

3 security gaps detected — browsers may warn visitors about your site.
Your LCP is 24.7s — fixing the 2 performance criticals could bring it under Google's 2.5s 'Good' threshold.

Conversion Barriers

3 critical 6 warning

9 barrier(s) likely increasing bounce by ~38%.

Speed (2)

Page takes 24.7s to load

+12% bounce

Users abandon at ~3s — you're 22.2s over the 2.5s threshold

Fix: Optimize render-blocking resources, preload the hero image, and compress images

Page feels frozen for 1.8s

+5% bounce

Clicks on the primary CTA are ignored while JavaScript runs

Fix: Break up long tasks; defer non-critical JavaScript to post-hydration

Trust (2)

No HSTS header

+1% bounce

Returning visitors are briefly exposed to downgrade attacks on first request

Fix: Set Strict-Transport-Security: max-age=31536000; includeSubDomains

No Content-Security-Policy header

+1% bounce

Higher XSS blast radius — one compromised script can exfiltrate the checkout form

Fix: Ship a reporting-only CSP first, then enforce once violations are clean

Usability (1)

No viewport meta tag

+15% bounce

Mobile browsers render at desktop width and shrink — text unreadable, tap targets miniature

Fix: Add <meta name="viewport" content="width=device-width, initial-scale=1">

Content (3)

No Open Graph tags

+2% bounce

Links shared on LinkedIn / Slack / Facebook show bare URLs — referral clicks drop

Fix: Add og:title, og:description, og:image, og:url to the page head

No structured data

+2% bounce

No rich-result eligibility in Google — lower SERP CTR vs competitors with stars and prices

Fix: Add JSON-LD for your page type (Product, Article, FAQPage, LocalBusiness, …)

Thin content

+3% bounce

Under 300 words — visitors bounce looking for substance, search engines rank competitors first

Fix: Add a substantive FAQ, product detail, or case-study section

Navigation (1)

No skip-to-content link

+1% bounce

Keyboard and screen-reader users must tab through the entire header on every page

Fix: Add a visible-on-focus <a href="#main">Skip to content</a> as the first focusable element

Preliminary CRO audit — each barrier links to the tab with detailed analysis.

Return on Investment

£413 investment → £0.80/month returns + GBP 18,050,000 risk avoided

Payback period: > 2 years First-year ROI: -98%

Investment

£413

6h · 5 findings

Monthly returns

£0.80 /mo

~£9.58 / year

  • Bandwidth savings £0.80

Regulatory risk avoided

GBP 18,050,000

if kept compliant

  • UK GDPR GBP 17,500,000
  • PECR GBP 500,000
  • Equality Act 2010 GBP 50,000

£113 — in quick wins — start here for the fastest payback

Figures combine localized regulatory fine ceilings, search/conversion value priced against local CPC, and bandwidth waste estimates. Results depend on implementation quality and audience composition. Not legal or financial advice.

Full methodology & sources

Estimated Remediation Cost

£413

5.5 developer hours at £75/hr

Based on United Kingdom rates (£75/hr)

Quick wins
£113 3 fixes in ~90 minutes

Start here for the best return on investment

Cost by category

Cost by effort level

Adjust assumptions
£ /hr

Rates reflect fully-loaded developer cost including overhead

How developer rates are sourced

What Inaction Is Costing You

£1,504,167 / month at risk

~£18,050,010 / year if left unfixed

Compliance Risk

£18,050,000

UK GDPRPECREquality Act 2010
  • No privacy policy link detected
    UK GDPR: GBP 10,000 – GBP 17,500,000
  • Trackers detected but no cookie policy found
    UK GDPR: GBP 10,000 – GBP 17,500,000
  • Trackers detected but no cookie policy found
    PECR: GBP 1,000 – GBP 500,000

+4 more

Bandwidth Waste

£0.80 /mo

12671.4 MB/mo × 0.063 GBP/GB

  • Optimize transfer: save ~1.3 MB per page load
    Saves £0.80/mo

Compliance figures represent the statutory maximum fine for the most severe triggered category, capped per regulation — not the sum of per-finding penalties. Based on published regulatory fine ranges. This is not legal advice.

Compliance methodology · SEO assumptions · Bandwidth model

Your performance is already good — improvements may show diminishing returns

Unique monthly visitors from your analytics

Purchases, signups, or key actions

Optional — for revenue estimation

additional conversions/month

more engaged visitors from reduced bounce

potential monthly revenue
Current bounce (est.)
After fixes (est.)
Estimated bounce reduction

Fix 4 critical issues to capture this value

How this is calculated

Based on Google/Deloitte research ("Milliseconds Make Millions") showing a ~7% bounce rate increase per additional second of LCP above the 2.5s "Good" threshold.

Your site's LCP: → estimated after fixes.

These are estimates based on industry research — actual results vary

Bounce-rate model & assumptions

Your data stays in your browser — nothing is sent to our servers

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Lighthouse Scores

Industry-standard audits powered by Google Lighthouse.

29
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

Core Web Vitals

Key metrics that affect user experience.

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

7.42 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

24.75 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

1.78 s

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.023

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

9.98 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

24.75 s

Detailed Report

Audit breakdown by category with detailed findings.

29

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Shipping ES5 transpiled code to modern browsers wastes bytes — every user with an evergreen browser pays for compatibility you don't need.

Learn more

Most users today run browsers that natively support ES6+, async/await, optional chaining, and the rest of modern JavaScript. Transpiling to ES5 'just in case' adds 20-40% to your bundle for no benefit. Configure your build to target a modern browserslist, or ship a differential bundle pair (modern + legacy) with the module/nomodule pattern.

Source: Google web.dev / Lighthouse

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

RequestCache TTLTransfer Size
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpg0.0 ms516.3 KiB
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff20.0 ms337.8 KiB
/api/v1/gw/static/js/main.www_bristol_ac_uk.hHsrG.v176849...3600.0 s295.1 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms146.4 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.js0.0 ms136.7 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.js0.0 ms123.8 KiB
app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=on14400.0 s143.6 KiB
app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce14400.0 s143.4 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms75.8 KiB
/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768...3600.0 s74.9 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms39.8 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms38.8 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms14.2 KiB
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svg0.0 ms12.2 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.js0.0 ms9.8 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms6.4 KiB
app.termly.io/resource-blocker/support/894-6156b36a131577c56e7e.min.js14400.0 s8.4 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.css0.0 ms2.0 KiB
app.termly.io/resource-blocker/support/524-7d36cb122791702e3df2.min.js14400.0 s2.7 KiB
/api/v1/gw/static/js/index.www_bristol_ac_uk.hHsrG.v17684...3600.0 s2.1 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms1.6 KiB
app.termly.io/resource-blocker/support/861-8c5cb8c2beda05e3176b.min.js14400.0 s2.3 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms1.5 KiB
app.termly.io/resource-blocker/support/377-e518d8a5c599aa1c5977.min.js14400.0 s873 B

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Top function call valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:9.733 source:map[column:2967 line:1 type:source-location url:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js urlProvider:network]]]
headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:103.662 source:map[type:text value:[unattributed]]] map[reflowTime:10.8 source:map[column:3645 line:0 type:source-location url:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js urlProvider:network]] map[reflowTime:3.839 source:map[column:10381 line:1 type:source-location url:https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js urlProvider:network]] map[reflowTime:0.17 source:map[column:11721 line:1 type:source-location url:https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js urlProvider:network]] map[reflowTime:0.995 source:map[column:20619 line:1 type:source-location url:https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js urlProvider:network]]]

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLResource SizeEst Savings
Stone buildings, blue sky, green grass, gazebos and people body > main#main > section#homepage-hero > div.hero__image
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpg516.0 KiB310.2 KiB

Each subpart has specific improvement strategies. Ideally, most of the LCP time should be spent on loading the resources, not within delays.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:label label:Subpart valueType:text] map[key:duration label:Duration valueType:ms]]
items: [map[duration:2059.472 label:Time to first byte subpart:timeToFirstByte] map[duration:387.162 label:Resource load delay subpart:resourceLoadDelay] map[duration:1515.197 label:Resource load duration subpart:resourceLoadDuration] map[duration:53.135 label:Element render delay subpart:elementRenderDelay]]
lhId: page-0-DIV
nodeLabel: Stone buildings, blue sky, green grass, gazebos and people
path: 1,HTML,1,BODY,5,MAIN,0,SECTION,0,DIV
selector: body > main#main > section#homepage-hero > div.hero__image
snippet: <div class="hero__image" role="img" aria-hidden="true" aria-label="Stone buildings, blue sky, green grass, gazebos and people" style="background-image: url(&quot;/media-library/sites/homepage/images/homepage-1.jpg…&quot;);">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLProtocol
www.bristol.ac.uk/http/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/site.webmanifesthttp/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpghttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.csshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.jshttp/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svghttp/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-28001222.14b11faa.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d0a34cd.1234590d.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d20feaa.4d2e4f39.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d21aed6.b0d07fb6.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-302d1d6c.2e55e9a6.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-52a156f6.e16faf2a.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-575938b4.4fff889e.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b8a8a66.6a8d6c5b.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b8c1bbe.2251dfd4.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b9f65f9.5cee4974.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-8f23d30c.60b2b46c.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-a384c412.a729884a.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-c2c50296.636f0170.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-e319960a.f2ce602d.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/polyfills-core-js.1b2c641f.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/polyfills-dom.70590cdd.jshttp/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff2http/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/favicon.icohttp/1.1

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.
title: Preconnected origins
value: no origins were preconnected
description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.
title: Preconnect candidates

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 1.3 s
URLTime Spent
bris.ac.uk/1.3 s
www.bristol.ac.uk/0.0 ms

The maximum potential First Input Delay that your users could experience is the duration of the longest task. Learn more about the Maximum Potential First Input Delay metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Diagnostics

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Multi-megabyte JavaScript bundles delay every interactive feature on the page.

Learn more

This is the Lighthouse audit fired when too much JS is shipped relative to what executes. The fix isn't a config flag — it requires bundle analysis (webpack-bundle-analyzer, rollup-plugin-visualizer), splitting routes into chunks, lazy-loading off-screen components, and removing unused dependencies. Fundamentally different from minification: minifying reduces byte count, this reduces what's downloaded at all.

Source: Google web.dev / Lighthouse

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to reduce Javascript execution time.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this. Learn how to minimize main-thread work

Why this matters

Performance issues directly impact user engagement and conversion rates.

CategoryTime Spent
Script Evaluation2.4 s
Other1.1 s
Style & Layout1.1 s
Rendering379 ms
Script Parsing & Compilation296 ms
Parse HTML & CSS97 ms
Garbage Collection63 ms

Many navigations are performed by going back to a previous page, or forwards again. The back/forward cache (bfcache) can speed up these return navigations. Learn more about the bfcache

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failure reasonFailure type
The page has an unload handler in the main frame.Actionable

More information about the performance of your application. These numbers don't directly affect the Performance score.

Layout shift culprits
Optimize DOM size
Font display
LCP request discovery
Optimize viewport for mobile
Minify CSS
Minify JavaScript
Avoid long main-thread tasks 15 long tasks found
Avoid non-composited animations 7 animated elements found
Image elements have explicit `width` and `height`
Network Requests
Network Round Trip Times 200 ms
Server Backend Latencies 210 ms
Tasks
Diagnostics
Metrics
Screenshot Thumbnails
Final Screenshot
Script Treemap Data
Resources Summary
Initial server response time was short Root document took 530 ms
Avoid large layout shifts 5 layout shifts found
INP breakdown
User Timing marks and measures
96

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

ARIA

ARIA dialog elements without accessible names may prevent screen readers users from discerning the purpose of these elements. Learn how to make ARIA dialog elements more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
We use essential cookies to make our site work. With your consent, we may also … div#termly-code-snippet-support > div > div.termly-styles-root-f9c495 > div.termly-styles-consent-banner-fa199d

These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.

Names and labels

Including a skip link can help users skip to the main content to save time. Learn more about skip links.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Skip to site navigation nav > ul.list > li.list__item > a.list__link

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Interactive controls are keyboard focusable
Interactive elements indicate their purpose and state
The page has a logical tab order
Visual order on the page follows DOM order
User focus is not accidentally trapped in a region
The user's focus is directed to new content added to the page
HTML5 landmark elements are used to improve navigation
Offscreen content is hidden from assistive technology
Custom controls have associated labels
Custom controls have ARIA roles
`[aria-*]` attributes match their roles
`[aria-hidden="true"]` is not present on the document `<body>`
`[role]`s have all required `[aria-*]` attributes
`[role]` values are valid
`[aria-*]` attributes have valid values
`[aria-*]` attributes are valid and not misspelled
Buttons have an accessible name
Image elements have `[alt]` attributes
Form elements have associated labels
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
Select elements have associated label elements.
`button`, `link`, and `menuitem` elements have accessible names
ARIA attributes are used as specified for the element's role
`[aria-hidden="true"]` elements do not contain focusable descendents
Elements use only permitted ARIA attributes
Background and foreground colors have a sufficient contrast ratio
`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
Definition list items are wrapped in `<dl>` elements
Document has a `<title>` element
`<html>` element has a `[lang]` attribute
`<html>` element has a valid value for its `[lang]` attribute
Links have a discernible name
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
No element has a `[tabindex]` value greater than 0
Touch targets have sufficient size and spacing.
Heading elements appear in a sequentially-descending order
Document has a main landmark.
Deprecated ARIA roles were not used
`[accesskey]` values are unique
ARIA input fields have accessible names
ARIA `meter` elements have accessible names
ARIA `progressbar` elements have accessible names
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
`[role]`s are contained by their required parent element
Elements with the `role=text` attribute do not have focusable descendents.
ARIA toggle fields have accessible names
ARIA `tooltip` elements have accessible names
ARIA `treeitem` elements have accessible names
The page contains a heading, skip link, or landmark region
ARIA IDs are unique
No form fields have multiple labels
`<frame>` or `<iframe>` elements have a title
`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.
Input buttons have discernible text.
`<input type="image">` elements have `[alt]` text
Links are distinguishable without relying on color.
The document does not use `<meta http-equiv="refresh">`
`<object>` elements have alternate text
Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.
`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.
`[lang]` attributes have a valid value
`<video>` elements contain a `<track>` element with `[kind="captions"]`
Tables have different content in the summary attribute and `<caption>`.
All heading elements contain content.
Uses ARIA roles only on compatible elements
Image elements do not have `[alt]` attributes that are redundant text.
Identical links have the same purpose.
Elements with visible text labels have matching accessible names.
Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
`<td>` elements in a large `<table>` have one or more table headers.
77

Best Practices

General

Deprecated APIs will eventually be removed from the browser. Learn more about deprecated APIs.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Deprecation / WarningSource
Unload event listeners are deprecated and will be removed.

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more about this errors in console diagnostic audit

Why this matters

Performance issues directly impact user engagement and conversion rates.

SourceDescription
Uncaught Error: Termly resource blocker has already been loaded on this page. Check your markup for duplicate <script> tags including https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce
Uses HTTPS
Avoids third-party cookies
Allows users to paste into input fields
Avoids requesting the geolocation permission on page load
Avoids requesting the notification permission on page load
Displays images with correct aspect ratio
Serves images with appropriate resolution
Page has the HTML doctype
Properly defines charset
No issues in the `Issues` panel in Chrome Devtools
Ensure CSP is effective against XSS attacks
Use a strong HSTS policy
Ensure proper origin isolation with COOP
Mitigate clickjacking with XFO or CSP
Mitigate DOM-based XSS with Trusted Types
Detected JavaScript libraries
Page has valid source maps
Redirects HTTP traffic to HTTPS
100

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Structured data is valid
Page isn’t blocked from indexing
Document has a `<title>` element
Document has a meta description
Page has successful HTTP status code
Links have descriptive text
Links are crawlable
Image elements have `[alt]` attributes
Document has a valid `hreflang`
robots.txt is valid
Document has a valid `rel=canonical`

Lighthouse Scores

Industry-standard audits powered by Google Lighthouse. — Desktop

42
Performance Overall performance score (0–100) based on Core Web Vitals and other metrics. 90+ is good.
96
Accessibility Measures how accessible the page is for users with disabilities. Checks color contrast, ARIA labels, and semantic HTML.
77
Best Practices Checks for modern web development best practices including HTTPS, no console errors, and secure JavaScript.
100
SEO Measures basic SEO optimizations: meta tags, crawlability, link text, and mobile friendliness.

Core Web Vitals

Key metrics that affect user experience. — Desktop

First Contentful Paint First Contentful Paint — how long until the browser renders the first piece of content. Under 1.8s is good.

3.61 s

Largest Contentful Paint Largest Contentful Paint — how long until the largest visible element loads. Under 2.5s is good.

6.27 s

Total Blocking Time Total Blocking Time — total time the main thread was blocked, preventing user input. Under 200ms is good.

93 ms

Cumulative Layout Shift Cumulative Layout Shift — measures visual stability. How much the page layout shifts during loading. Under 0.1 is good.

0.271

Speed Index Speed Index — how quickly content is visually displayed during load. Under 3.4s is good.

4.15 s

Time to Interactive Time to Interactive — how long until the page is fully interactive and responds to user input. Under 3.8s is good.

6.27 s

Detailed Report

Audit breakdown by category with detailed findings.

42

Performance

Insights

Remove large, duplicate JavaScript modules from bundles to reduce unnecessary bytes consumed by network activity.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Polyfills and transforms enable older browsers to use new JavaScript features. However, many aren't necessary for modern browsers. Consider modifying your JavaScript build process to not transpile Baseline features, unless you know you must support older browsers. Learn why most sites can deploy ES6+ code without transpiling

Why this matters

Shipping ES5 transpiled code to modern browsers wastes bytes — every user with an evergreen browser pays for compatibility you don't need.

Learn more

Most users today run browsers that natively support ES6+, async/await, optional chaining, and the rest of modern JavaScript. Transpiling to ES5 'just in case' adds 20-40% to your bundle for no benefit. Configure your build to target a modern browserslist, or ship a differential bundle pair (modern + legacy) with the module/nomodule pattern.

Source: Google web.dev / Lighthouse

3rd party code can significantly impact load performance. Reduce and defer loading of 3rd party code to prioritize your page's content.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A long cache lifetime can speed up repeat visits to your page. Learn more about caching.

Why this matters

Performance issues directly impact user engagement and conversion rates.

RequestCache TTLTransfer Size
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpg0.0 ms516.3 KiB
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff20.0 ms337.8 KiB
/api/v1/gw/static/js/main.www_bristol_ac_uk.hHsrG.v176849...3600.0 s295.3 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms146.4 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.js0.0 ms136.7 KiB
/media-library/sites/aa/images/homepage/bristol-banner-on...0.0 ms130.6 KiB
www.bristol.ac.uk/media-library/sites/homepage/images/4547_10015456.jpg0.0 ms127.8 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.js0.0 ms123.8 KiB
/assets/responsive-web-project/2.7.0/fonts/fontawesome/fa...0.0 ms99.2 KiB
app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce?autoBlock=on14400.0 s143.5 KiB
app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce14400.0 s143.5 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms75.8 KiB
www.bristol.ac.uk/media-library/sites/homepage/images/mumbai-homepage-2.jpg0.0 ms63.3 KiB
/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768...3600.0 s74.8 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms39.8 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms38.8 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms14.2 KiB
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svg0.0 ms12.2 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.js0.0 ms9.8 KiB
/assets/responsive-web-project/2.7.0/css/responsive-web-p...0.0 ms6.4 KiB
app.termly.io/resource-blocker/support/894-6156b36a131577c56e7e.min.js14400.0 s8.4 KiB
www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.css0.0 ms2.0 KiB
app.termly.io/resource-blocker/support/524-7d36cb122791702e3df2.min.js14400.0 s2.7 KiB
/api/v1/gw/static/js/index.www_bristol_ac_uk.hHsrG.v17684...3600.0 s2.1 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms1.6 KiB
app.termly.io/resource-blocker/support/861-8c5cb8c2beda05e3176b.min.js14400.0 s2.3 KiB
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...0.0 ms1.5 KiB
app.termly.io/resource-blocker/support/377-e518d8a5c599aa1c5977.min.js14400.0 s873 B

Layout shifts occur when elements move absent any user interaction. Investigate the causes of layout shifts, such as elements being added, removed, or their fonts changing as the page loads.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:node label:Element subItemsHeading:map[key:extra] valueType:node] map[granularity:0.001 key:score label:Layout shift score subItemsHeading:map[key:cause valueType:text] valueType:numeric]]
items: [map[node:map[type:text value:Total] score:0.271048] map[node:map[boundingRect:map[bottom:1320 height:448 left:0 right:1350 top:872 width:1350] lhId:page-5-SECTION nodeLabel:Open events and virtual visits Visit us on campus or attend an online event to… path:1,HTML,1,BODY,9,MAIN,2,SECTION selector:body > main#main > section.block snippet:<section class="block block--grid bg-white" data-block-modifier="homepage-open-events"> type:node] score:0.253058] map[node:map[boundingRect:map[bottom:1224 height:256 left:15 right:1335 top:968 width:1320] lhId:page-12-DIV nodeLabel:Open events and virtual visits Visit us on campus or attend an online event to… path:1,HTML,1,BODY,9,MAIN,2,SECTION,0,DIV selector:body > main#main > section.block > div.container snippet:<div class="container"> type:node] score:0.008423 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:136 height:52 left:35 right:215 top:84 width:180] lhId:page-26-IMG nodeLabel:University of Bristol logo path:1,HTML,1,BODY,4,HEADER,1,DIV,0,DIV,0,A,0,IMG selector:div.header__main > div.header__logo > a > img snippet:<img src="/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svg" alt="University of Bristol logo" width="180" height="52"> type:node]] map[cause:Web font extra:map[type:url value:https://fonts.gstatic.com/s/materialsymbolsrounded/v330/sykO-zNym6YjUruM-QrEh7-nyTnjDwKNJ_190FjpZIvLgyidOK7BDB_Qb9vUdV6_gjDK-P1Ju0XXkRzDgw.woff2]]] type:subitems]] map[node:map[boundingRect:map[bottom:1320 height:448 left:0 right:1350 top:872 width:1350] lhId:page-5-SECTION nodeLabel:Open events and virtual visits Visit us on campus or attend an online event to… path:1,HTML,1,BODY,9,MAIN,2,SECTION selector:body > main#main > section.block snippet:<section class="block block--grid bg-white" data-block-modifier="homepage-open-events"> type:node] score:0.006384 subItems:map[items:[map[cause:Web font extra:map[type:url value:https://fonts.gstatic.com/s/opensans/v44/memvYaGs126MiZpBA-UvWbX2vVnXBbObj2OVTS-mu0SC55I.woff2]] map[cause:Web font extra:map[type:url value:https://fonts.gstatic.com/s/opensans/v44/memQYaGs126MiZpBA-UFUIcVXSCEkx2cmqvXlWq8tWZ0Pw86hd0Rk8ZkWVAewIMUdjFXmQ.woff2]]] type:subitems]] map[node:map[boundingRect:map[bottom:468 height:208 left:253 right:1097 top:260 width:843] lhId:page-4-DIV nodeLabel:Undergraduate open days path:1,HTML,1,BODY,9,MAIN,0,SECTION,1,DIV,0,DIV,0,DIV selector:section#homepage-hero > div.container > div.hero__content > div.hero__main snippet:<div class="hero__main"> type:node] score:0.002426 subItems:map[items:[map[cause:Unsized image element extra:map[boundingRect:map[bottom:136 height:52 left:35 right:215 top:84 width:180] lhId:page-26-IMG nodeLabel:University of Bristol logo path:1,HTML,1,BODY,4,HEADER,1,DIV,0,DIV,0,A,0,IMG selector:div.header__main > div.header__logo > a > img snippet:<img src="/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svg" alt="University of Bristol logo" width="180" height="52"> type:node]] map[cause:Web font extra:map[type:url value:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff2]] map[cause:Web font extra:map[type:url value:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/fontawesome/fa-brands-400.woff2]]] type:subitems]] map[node:map[boundingRect:map[bottom:1320 height:448 left:0 right:1350 top:872 width:1350] lhId:page-5-SECTION nodeLabel:Open events and virtual visits Visit us on campus or attend an online event to… path:1,HTML,1,BODY,9,MAIN,2,SECTION selector:body > main#main > section.block snippet:<section class="block block--grid bg-white" data-block-modifier="homepage-open-events"> type:node] score:0.000757]]

Your first network request is the most important. Reduce its latency by avoiding redirects, ensuring a fast server response, and enabling text compression.

Why this matters

Performance issues directly impact user engagement and conversion rates.

A forced reflow occurs when JavaScript queries geometric properties (such as offsetWidth) after styles have been invalidated by a change to the DOM state. This can result in poor performance. Learn more about forced reflows and possible mitigations.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:source label:Top function call valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:5.682 source:map[column:2967 line:1 type:source-location url:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js urlProvider:network]]]
headings: [map[key:source label:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]
items: [map[reflowTime:129.671 source:map[type:text value:[unattributed]]] map[reflowTime:9.659 source:map[column:3478 line:0 type:source-location url:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js urlProvider:network]] map[reflowTime:1.324 source:map[column:12918 line:0 type:source-location url:https://www.bristol.ac.uk/assets/responsive-web-project/2.7.0/js/responsive-web-project-main-2.7.0.js urlProvider:network]] map[reflowTime:0.486 source:map[column:11721 line:1 type:source-location url:https://eu.gw.fortiabp.forticloud.com/api/v1/gw/static/js/vendor.www_bristol_ac_uk.hHsrG.v1768494982.js urlProvider:network]]]

Reducing the download time of images can improve the perceived load time of the page and LCP. Learn more about optimizing image size

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLResource SizeEst Savings
Stone buildings, blue sky, green grass, gazebos and people body > main#main > section#homepage-hero > div.hero__image
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpg516.0 KiB310.2 KiB
Members of the public cross a bridge over a river. On the side of the bridge is… div.module > a.module__link > div.module__media > div.module__image
/media-library/sites/aa/images/homepage/bristol-banner-on...130.3 KiB64.3 KiB
harbourside with blue sky and boats on the water div.module > a.module__link > div.module__media > div.module__image
www.bristol.ac.uk/media-library/sites/homepage/images/4547_10015456.jpg127.5 KiB58.9 KiB
A large body of water with a prominent building with a turret in the forefront.… div.module > a.module__link > div.module__media > div.module__image
www.bristol.ac.uk/media-library/sites/homepage/images/mumbai-homepage-2.jpg63.0 KiB36.6 KiB

Each subpart has specific improvement strategies. Ideally, most of the LCP time should be spent on loading the resources, not within delays.

Why this matters

Performance issues directly impact user engagement and conversion rates.

headings: [map[key:label label:Subpart valueType:text] map[key:duration label:Duration valueType:ms]]
items: [map[duration:2100.098 label:Time to first byte subpart:timeToFirstByte] map[duration:388.1 label:Resource load delay subpart:resourceLoadDelay] map[duration:1400.309 label:Resource load duration subpart:resourceLoadDuration] map[duration:88.38 label:Element render delay subpart:elementRenderDelay]]
lhId: page-0-DIV
nodeLabel: Stone buildings, blue sky, green grass, gazebos and people
path: 1,HTML,1,BODY,9,MAIN,0,SECTION,0,DIV
selector: body > main#main > section#homepage-hero > div.hero__image
snippet: <div class="hero__image" role="img" aria-hidden="true" aria-label="Stone buildings, blue sky, green grass, gazebos and people" style="background-image: url(&quot;/media-library/sites/homepage/images/homepage-1.jpg…&quot;);">

HTTP/2 and HTTP/3 offer many benefits over HTTP/1.1, such as multiplexing. Learn more about using modern HTTP.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLProtocol
www.bristol.ac.uk/http/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/site.webmanifesthttp/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
/assets/responsive-web-project/2.7.0/css/responsive-web-p...http/1.1
www.bristol.ac.uk/media-library/sites/homepage/images/homepage-1.jpghttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/css/app.565b7505.csshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/app.12148122.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-vendors.a3cb5fa7.jshttp/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/images/logos/uob-logo.svghttp/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
/assets/responsive-web-project/2.7.0/js/responsive-web-pr...http/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-28001222.14b11faa.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d0a34cd.1234590d.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d20feaa.4d2e4f39.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-2d21aed6.b0d07fb6.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-302d1d6c.2e55e9a6.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-480a6038.24fe62bd.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-52a156f6.e16faf2a.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-575938b4.4fff889e.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b8a8a66.6a8d6c5b.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b8c1bbe.2251dfd4.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-7b9f65f9.5cee4974.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-8f23d30c.60b2b46c.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-a384c412.a729884a.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-c2c50296.636f0170.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/chunk-e319960a.f2ce602d.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/polyfills-core-js.1b2c641f.jshttp/1.1
www.bristol.ac.uk/assets/homepage-search/1.0.4/js/polyfills-dom.70590cdd.jshttp/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/fonts/inter/Inter.woff2http/1.1
/assets/responsive-web-project/2.7.0/fonts/fontawesome/fa...http/1.1
www.bristol.ac.uk/assets/responsive-web-project/2.7.0/favicons/favicon.icohttp/1.1
www.bristol.ac.uk/media-library/sites/homepage/images/4547_10015456.jpghttp/1.1
www.bristol.ac.uk/media-library/sites/homepage/images/mumbai-homepage-2.jpghttp/1.1
/media-library/sites/aa/images/homepage/bristol-banner-on...http/1.1

Avoid chaining critical requests by reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load.

Why this matters

Performance issues directly impact user engagement and conversion rates.

description: [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints help the browser establish a connection earlier in the page load, saving time when the first request for that origin is made. The following are the origins that the page preconnected to.
title: Preconnected origins
value: no origins were preconnected
description: Add [preconnect](https://developer.chrome.com/docs/lighthouse/performance/uses-rel-preconnect/) hints to your most important origins, but try to use no more than 4.
title: Preconnect candidates

Requests are blocking the page's initial render, which may delay LCP. Deferring or inlining can move these network requests out of the critical path.

Why this matters

Performance issues directly impact user engagement and conversion rates.

These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.

Redirects introduce additional delays before the page can be loaded. Learn how to avoid page redirects.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 783 ms
URLTime Spent
bris.ac.uk/783 ms
www.bristol.ac.uk/0.0 ms

These are the largest layout shifts observed on the page. Each table item represents a single layout shift, and shows the element that shifted the most. Below each item are possible root causes that led to the layout shift. Some of these layout shifts may not be included in the CLS metric value due to windowing. Learn how to improve CLS

Why this matters

Performance issues directly impact user engagement and conversion rates.

ElementLayout shift score
Open events and virtual visits Visit us on campus or attend an online event to… body > main#main > section.block
0.253
Open events and virtual visits Visit us on campus or attend an online event to… body > main#main > section.block > div.container
0.008
Open events and virtual visits Visit us on campus or attend an online event to… body > main#main > section.block
0.006
Undergraduate open days section#homepage-hero > div.container > div.hero__content > div.hero__main
0.002
Open events and virtual visits Visit us on campus or attend an online event to… body > main#main > section.block
0.001

Time to Interactive is the amount of time it takes for the page to become fully interactive. Learn more about the Time to Interactive metric.

Why this matters

Performance issues directly impact user engagement and conversion rates.

TTI

Diagnostics

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity. Learn how to reduce unused CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

Why this matters

Multi-megabyte JavaScript bundles delay every interactive feature on the page.

Learn more

This is the Lighthouse audit fired when too much JS is shipped relative to what executes. The fix isn't a config flag — it requires bundle analysis (webpack-bundle-analyzer, rollup-plugin-visualizer), splitting routes into chunks, lazy-loading off-screen components, and removing unused dependencies. Fundamentally different from minification: minifying reduces byte count, this reduces what's downloaded at all.

Source: Google web.dev / Lighthouse

Many navigations are performed by going back to a previous page, or forwards again. The back/forward cache (bfcache) can speed up these return navigations. Learn more about the bfcache

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failure reasonFailure type
The page has an unload handler in the main frame.Actionable

More information about the performance of your application. These numbers don't directly affect the Performance score.

Max Potential First Input Delay 120 ms
Optimize DOM size
Font display
LCP request discovery
Optimize viewport for mobile
Minify CSS
Minify JavaScript
JavaScript execution time 0.5 s
Minimizes main-thread work 1.6 s
Avoid long main-thread tasks 6 long tasks found
Avoid non-composited animations 7 animated elements found
Image elements have explicit `width` and `height`
Network Requests
Network Round Trip Times 200 ms
Server Backend Latencies 210 ms
Tasks
Diagnostics
Metrics
Screenshot Thumbnails
Final Screenshot
Script Treemap Data
Resources Summary
Initial server response time was short Root document took 580 ms
INP breakdown
User Timing marks and measures
96

Accessibility

These checks highlight opportunities to improve the accessibility of your web app. Automatic detection can only detect a subset of issues and does not guarantee the accessibility of your web app, so manual testing is also encouraged.

ARIA

ARIA dialog elements without accessible names may prevent screen readers users from discerning the purpose of these elements. Learn how to make ARIA dialog elements more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
We use essential cookies to make our site work. With your consent, we may also … div#termly-code-snippet-support > div > div.termly-styles-root-f9c495 > div.termly-styles-consent-banner-fa199d

These are opportunities to improve the usage of ARIA in your application which may enhance the experience for users of assistive technology, like a screen reader.

Names and labels

Including a skip link can help users skip to the main content to save time. Learn more about skip links.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Skip to site navigation nav > ul.list > li.list__item > a.list__link

These are opportunities to improve the semantics of the controls in your application. This may enhance the experience for users of assistive technology, like a screen reader.

Interactive controls are keyboard focusable
Interactive elements indicate their purpose and state
The page has a logical tab order
Visual order on the page follows DOM order
User focus is not accidentally trapped in a region
The user's focus is directed to new content added to the page
HTML5 landmark elements are used to improve navigation
Offscreen content is hidden from assistive technology
Custom controls have associated labels
Custom controls have ARIA roles
`[aria-*]` attributes match their roles
`[aria-hidden="true"]` is not present on the document `<body>`
`[role]`s have all required `[aria-*]` attributes
`[role]` values are valid
`[aria-*]` attributes have valid values
`[aria-*]` attributes are valid and not misspelled
Buttons have an accessible name
Image elements have `[alt]` attributes
Form elements have associated labels
`[user-scalable="no"]` is not used in the `<meta name="viewport">` element and the `[maximum-scale]` attribute is not less than 5.
Select elements have associated label elements.
`button`, `link`, and `menuitem` elements have accessible names
ARIA attributes are used as specified for the element's role
`[aria-hidden="true"]` elements do not contain focusable descendents
Elements use only permitted ARIA attributes
Background and foreground colors have a sufficient contrast ratio
`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
Definition list items are wrapped in `<dl>` elements
Document has a `<title>` element
`<html>` element has a `[lang]` attribute
`<html>` element has a valid value for its `[lang]` attribute
Links have a discernible name
Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
No element has a `[tabindex]` value greater than 0
Touch targets have sufficient size and spacing.
Heading elements appear in a sequentially-descending order
Document has a main landmark.
Deprecated ARIA roles were not used
Elements with visible text labels have matching accessible names.
`[accesskey]` values are unique
ARIA input fields have accessible names
ARIA `meter` elements have accessible names
ARIA `progressbar` elements have accessible names
Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
`[role]`s are contained by their required parent element
Elements with the `role=text` attribute do not have focusable descendents.
ARIA toggle fields have accessible names
ARIA `tooltip` elements have accessible names
ARIA `treeitem` elements have accessible names
The page contains a heading, skip link, or landmark region
ARIA IDs are unique
No form fields have multiple labels
`<frame>` or `<iframe>` elements have a title
`<html>` element has an `[xml:lang]` attribute with the same base language as the `[lang]` attribute.
Input buttons have discernible text.
`<input type="image">` elements have `[alt]` text
Links are distinguishable without relying on color.
The document does not use `<meta http-equiv="refresh">`
`<object>` elements have alternate text
Cells in a `<table>` element that use the `[headers]` attribute refer to table cells within the same table.
`<th>` elements and elements with `[role="columnheader"/"rowheader"]` have data cells they describe.
`[lang]` attributes have a valid value
`<video>` elements contain a `<track>` element with `[kind="captions"]`
Tables have different content in the summary attribute and `<caption>`.
All heading elements contain content.
Uses ARIA roles only on compatible elements
Image elements do not have `[alt]` attributes that are redundant text.
Identical links have the same purpose.
Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
`<td>` elements in a large `<table>` have one or more table headers.
77

Best Practices

General

Deprecated APIs will eventually be removed from the browser. Learn more about deprecated APIs.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Deprecation / WarningSource
Unload event listeners are deprecated and will be removed.

Errors logged to the console indicate unresolved problems. They can come from network request failures and other browser concerns. Learn more about this errors in console diagnostic audit

Why this matters

Performance issues directly impact user engagement and conversion rates.

SourceDescription
Uncaught Error: Termly resource blocker has already been loaded on this page. Check your markup for duplicate <script> tags including https://app.termly.io/resource-blocker/f00d1986-fa46-46cf-a165-30f04408b1ce
Uses HTTPS
Avoids third-party cookies
Allows users to paste into input fields
Avoids requesting the geolocation permission on page load
Avoids requesting the notification permission on page load
Displays images with correct aspect ratio
Serves images with appropriate resolution
Page has the HTML doctype
Properly defines charset
No issues in the `Issues` panel in Chrome Devtools
Ensure CSP is effective against XSS attacks
Use a strong HSTS policy
Ensure proper origin isolation with COOP
Mitigate clickjacking with XFO or CSP
Mitigate DOM-based XSS with Trusted Types
Detected JavaScript libraries
Page has valid source maps
Redirects HTTP traffic to HTTPS
100

SEO

These checks ensure that your page is following basic search engine optimization advice. There are many additional factors Lighthouse does not score here that may affect your search ranking, including performance on Core Web Vitals. Learn more about Google Search Essentials.

Structured data is valid
Page isn’t blocked from indexing
Document has a `<title>` element
Document has a meta description
Page has successful HTTP status code
Links have descriptive text
Links are crawlable
Image elements have `[alt]` attributes
Document has a valid `hreflang`
robots.txt is valid
Document has a valid `rel=canonical`

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