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Lighthouse Desktop

· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.
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Detailed Report

Audit breakdown by category with detailed findings.

94

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

Performance issues directly impact user engagement and conversion rates.

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
cdn.ucl.ac.uk/fonts/dm-sans/DMSans[opsz,wght].woff214400.0 s90.6 KiB
i.ytimg.com/vi_webp/jxYFg3ygMgk/sddefault.webp7200.0 s55.6 KiB
i.ytimg.com/vi_webp/fibAxF6t11o/sddefault.webp7200.0 s50.4 KiB
cookie-consent.ucl.ac.uk/dist/ucl-consent.ui-full.min.js14400.0 s15.1 KiB
/home/sites/home/files/styles/homepage_hero_laptop/public...604800.0 s93.7 KiB
cookie-consent.ucl.ac.uk/dist/ucl-consent.blocker.min.js14400.0 s12.8 KiB
/home/sites/home/files/styles/content_cards_portrait_desk...604800.0 s40.8 KiB
/home/sites/home/files/styles/3_2_image_desktop/public/20...604800.0 s36.8 KiB
/news/sites/news/files/styles/medium_image/public/moorfie...604800.0 s32.0 KiB
/home/sites/home/files/styles/3_2_image_desktop/public/20...604800.0 s27.5 KiB
/news/sites/news/files/styles/medium_image/public/gut_mic...604800.0 s25.5 KiB
/news/sites/news/files/styles/medium_image/public/helen_c...604800.0 s24.1 KiB
/home/sites/home/files/styles/content_cards_portrait_desk...604800.0 s19.3 KiB
/news/sites/news/files/styles/medium_image/public/casey_w...604800.0 s18.1 KiB
/news/sites/news/files/styles/medium_image/public/patch_c...604800.0 s10.9 KiB
/news/sites/news/files/styles/medium_image/public/mouse_v...604800.0 s9.7 KiB
cdn.ucl.ac.uk/logos/ucl/ucl-logo--primary.svg14400.0 s943 B
cdn.ucl.ac.uk/logos/ucl/ucl-logo--secondary-inverted.svg14400.0 s795 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:31.117 source:map[column:22 line:19 type:source-location url:https://www.ucl.ac.uk/home/core/misc/drupal.init.js?v=10.4.8 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:31.117 source:map[column:268 line:0 type:source-location url:https://www.ucl.ac.uk/home/themes/custom/indigo/dist/js/03-organisms/quick-links/quick-links.drupal.js?tctc50 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
World-class eye health centre in London named div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image
/news/sites/news/files/styles/medium_image/public/moorfie...31.8 KiB22.7 KiB
Illuminated portico for UCL 200 event div.homepage-hero__media > div.media > picture > img
/home/sites/home/files/styles/homepage_hero_laptop/public...93.4 KiB21.3 KiB
UCL portico Bazaar and Fete 1909 div.spotlight__image > div.media > picture > img
/home/sites/home/files/styles/3_2_image_desktop/public/20...36.6 KiB19.1 KiB
Gut microbiome changes may signal Parkinson's disease risk div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image
/news/sites/news/files/styles/medium_image/public/gut_mic...25.3 KiB16.2 KiB
Life-changing drug identified for children with rare epilepsy div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image
/news/sites/news/files/styles/medium_image/public/helen_c...24.0 KiB14.8 KiB
UCL Portico Feb 26 div.base-card__image > div.media > picture > img
/home/sites/home/files/styles/content_cards_portrait_desk...40.6 KiB14.5 KiB
UCL 9th in the World - QS 2026 div.spotlight__image > div.media > picture > img
/home/sites/home/files/styles/3_2_image_desktop/public/20...27.4 KiB14.3 KiB
Engineered tissue offers hope for babies born with missing food pipe section div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image
/news/sites/news/files/styles/medium_image/public/casey_w...17.9 KiB8.7 KiB
Hormone patches effective for locally advanced prostate cancer div.base-card > div.base-card__container > div.base-card__image > img.funnelback-image
/news/sites/news/files/styles/medium_image/public/patch_c...10.7 KiB4.3 KiB

Optimize LCP by making the LCP image discoverable from the HTML immediately, and avoiding lazy-loading

Why this matters

Performance issues directly impact user engagement and conversion rates.

lhId: page-1-IMG
nodeLabel: Illuminated portico for UCL 200 event
path: 1,HTML,1,BODY,2,DIV,0,DIV,1,DIV,1,DIV,0,DIV,1,DIV,0,DIV,0,PICTURE,4,IMG
selector: div.homepage-hero__media > div.media > picture > img
snippet: <img loading="eager" width="640" height="360" src="https://www.ucl.ac.uk/home/sites/home/files/styles/homepage_hero_laptop/pu…" alt="Illuminated portico for UCL 200 event">

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.

URLTransfer SizeDuration
www.ucl.ac.uk/home/themes/custom/indigo/dist/accordion.css?tctc50796 B
/home/themes/contrib/stable/css/core/components/progress....426 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/homepage-hero.css?tctc50848 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/pre-footer.css?tctc50351 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/embed-media.css?tctc50291 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/header.css?tctc502.1 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/feed-widget.css?tctc50467 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/pre-footer-card.css?tctc50582 B
/home/modules/contrib/oembed_lazyload/css/oembed-lazyload...389 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/back-to-top.css?tctc50232 B
/home/modules/contrib/paragraphs/css/paragraphs.unpublish...178 B
www.ucl.ac.uk/home/themes/contrib/stable/css/views/views.module.css?tctc50291 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/default.css?tctc50753 B
/home/modules/contrib/oembed_lazyload/css/oembed-lazyload...334 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/cta.css?tctc50201 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/whats-on-item.css?tctc50794 B
www.ucl.ac.uk/home/core/misc/drupalSettingsLoader.js?v=10.4.8469 B
www.ucl.ac.uk/home/core/assets/vendor/tabbable/index.umd.min.js?v=6.2.02.6 KiB
www.ucl.ac.uk/home/core/misc/debounce.js?v=10.4.8770 B
www.ucl.ac.uk/home/core/misc/message.js?v=10.4.82.7 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/social-menu.css?tctc50387 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/quick-link-accordion.css?tctc50782 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtm.js?tctc50628 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/spotlight.css?tctc50501 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtag.js?tctc50644 B
www.ucl.ac.uk/home/themes/contrib/stable/css/media/oembed.formatter.css?tctc50144 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/card-link.css?tctc50705 B
www.ucl.ac.uk/home/modules/contrib/google_tag/js/gtag.ajax.js?tctc50404 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/highlight-block.css?tctc50376 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/global-navigation.css?tctc501.7 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/embed-media-item.css?tctc50291 B
/home/modules/contrib/oembed_lazyload/modules/oembed_lazy...793 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/quick-links.css?tctc50403 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/base-card.css?tctc501.1 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/base.css?tctc5012.5 KiB
www.ucl.ac.uk/home/themes/contrib/stable/js/ajax.js?v=10.4.8317 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/whats-on.css?tctc50760 B
www.ucl.ac.uk/home/core/misc/drupal.init.js?v=10.4.8572 B
www.ucl.ac.uk/home/core/misc/announce.js?v=10.4.81.8 KiB
www.ucl.ac.uk/home/core/assets/vendor/once/once.min.js?v=1.0.1791 B
www.ucl.ac.uk/home/core/assets/vendor/jquery/jquery.min.js?v=3.7.133.6 KiB81 ms
www.ucl.ac.uk/home/core/misc/progress.js?v=10.4.81.9 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/cta-item.css?tctc50278 B
www.ucl.ac.uk/home/core/misc/drupal.js?v=10.4.86.9 KiB
/home/themes/contrib/stable/css/core/components/ajax-prog...592 B
www.ucl.ac.uk/home/modules/contrib/typogrify/assets/typogrify.css?tctc50348 B
www.ucl.ac.uk/home/core/misc/ajax.js?v=10.4.819.5 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/curated-cards.css?tctc50128 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/footer.css?tctc50940 B
www.ucl.ac.uk/home/core/assets/vendor/loadjs/loadjs.min.js?v=4.3.01.1 KiB
www.ucl.ac.uk/home/themes/custom/indigo/dist/menu.css?tctc50393 B
www.ucl.ac.uk/home/themes/custom/indigo/dist/basic-content.css?tctc50855 B
cookie-consent.ucl.ac.uk/dist/ucl-consent.blocker.min.js12.8 KiB218 ms

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

Diagnostics

Minifying JavaScript files can reduce payload sizes and script parse time. Learn how to minify JavaScript.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 80 ms 21.8 KiB
URLTransfer SizeEst Savings
www.ucl.ac.uk/home/core/misc/ajax.js?v=10.4.819.4 KiB13.6 KiB
www.ucl.ac.uk/home/core/misc/drupal.js?v=10.4.86.8 KiB5.4 KiB
www.ucl.ac.uk/home/core/misc/tabbingmanager.js?v=10.4.83.8 KiB2.8 KiB

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

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 80 ms 25.4 KiB
URLTransfer SizeEst Savings
www.ucl.ac.uk/home/core/assets/vendor/jquery/jquery.min.js?v=3.7.133.5 KiB25.4 KiB

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

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: 224 ms
URLTime Spent
ucl.ac.uk/224 ms
www.ucl.ac.uk/0.0 ms
●Layout shift culprits
●Optimize DOM size
●Font display
●LCP breakdown
●Modern HTTP
●Optimize viewport for mobile
●Time to Interactive 1.3 s
●Max Potential First Input Delay 30 ms
●Minify CSS
●Reduce unused CSS
●Avoids enormous network payloads Total size was 780 KiB
●JavaScript execution time 0.0 s
●Minimizes main-thread work 0.7 s
●Image elements have explicit `width` and `height`
●Page didn't prevent back/forward cache restoration
●Network Requests
●Network Round Trip Times 10 ms
●Server Backend Latencies 270 ms
●Tasks
●Diagnostics
●Metrics
●Screenshot Thumbnails
●Final Screenshot
●Script Treemap Data
●Resources Summary
●Initial server response time was short Root document took 120 ms
●Avoid large layout shifts 1 layout shift found
○INP breakdown
○User Timing marks and measures
○Avoid long main-thread tasks
○Avoid non-composited animations
97

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.

Contrast

Low-contrast text is difficult or impossible for many users to read. Link text that is discernible improves the experience for users with low vision. Learn how to make links distinguishable.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
UCL privacy policy div#ucl-privacy-banner > div.ucl-privacy-banner__policy-section > p.ucl-privacy-banner__policy-inline > a.ucl-privacy-banner__policy-link

These are opportunities to improve the legibility of your content.

Visible text labels that do not match the accessible name can result in a confusing experience for screen reader users. Learn more about accessible names.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
https://www.youtube.com/watch?v=jxYFg3ygMgk div.field > div.oembed-lazyload > div.ucl-privacy-placeholder > a.ucl-consent-gate__link
https://www.youtube.com/watch?v=fibAxF6t11o div.field > div.oembed-lazyload > div.ucl-privacy-placeholder > a.ucl-consent-gate__link
○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
●Elements with an ARIA `[role]` that require children to contain a specific `[role]` have all required children.
●`[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.
●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
●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
●All heading elements contain content.
●Identical links have the same purpose.
○`[accesskey]` values are unique
○`button`, `link`, and `menuitem` elements have accessible names
○Elements with `role="dialog"` or `role="alertdialog"` have accessible names.
○ARIA input fields have accessible names
○ARIA `meter` elements have accessible names
○ARIA `progressbar` elements have accessible names
○`[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
○`<dl>`'s contain only properly-ordered `<dt>` and `<dd>` groups, `<script>`, `<template>` or `<div>` elements.
○Definition list items are wrapped in `<dl>` elements
○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
○The document does not use `<meta http-equiv="refresh">`
○`<object>` elements have alternate text
○Select elements have associated label elements.
○Skip links are focusable.
○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>`.
○Uses ARIA roles only on compatible elements
○Image elements do not have `[alt]` attributes that are redundant text.
○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.
100

Best Practices

●Uses HTTPS
●Avoids deprecated APIs
●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 browser errors logged to the console
●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 DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
○Mitigate clickjacking with XFO or CSP
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
●robots.txt is valid
●Image elements have `[alt]` attributes
●Document has a valid `hreflang`
●Document has a valid `rel=canonical`

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