Lighthouse Mobile

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

SCORE

GRADE

FIX

REVIEW

PASS

INFO

Detailed Report

Audit breakdown by category with detailed findings.

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.

Request	Cache TTL	Transfer Size
cdn-ukwest.onetrust.com/scripttemplates/202510.2.0/otBannerSdk.js	86400.0 s	124.1 KiB
/consent/a3110129-5f04-4e81-9c5e-b494a7836315/OtAutoBlock.js	86400.0 s	16.8 KiB
cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js	86400.0 s	9.1 KiB
/logos/3137c8ec-cd0f-432b-aee6-3e825379023a/a3110129-5f04...	86400.0 s	7.3 KiB
cdn-ukwest.onetrust.com/logos/static/powered_by_logo.svg	86400.0 s	2.6 KiB

Consider setting font-display to swap or optional to ensure text is consistently visible. swap can be further optimized to mitigate layout shifts with font metric overrides.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Est Savings
cdn.sheffield.ac.uk/themes/custom/common/uos/fonts/HotMess.ttf	105 ms
/themes/custom/common/uos/fonts/source-sans-3-v15-latin-r...	5.0 ms
/themes/custom/common/uos/fonts/source-sans-3-v15-latin-7...	5.0 ms
/themes/custom/common/uos/fonts/SourceSerif4Roman-Regular...	5.0 ms

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:Source valueType:source-location] map[granularity:1 key:reflowTime label:Total reflow time valueType:ms]]

items: [map[reflowTime:51.58 source:map[column:18292 line:83 type:source-location url:https://cdn.sheffield.ac.uk/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3NPhvqQHjM6Kpo.js?scope=footer&delta=0&language=en&theme=uos_public&include=eJxNjEEKgDAMBD9U7JNCm0ap1q7G5KCvFxHE28wchhcp1aCUmKGlosePhlHRTXoJ8-6iJ3ml5AbGujUxiX8JjoM2z61ynBpyauFyzTTCe0n2jN98A0vELbc urlProvider:network]] map[reflowTime:0.351 source:map[column:50335 line:2 type:source-location url:https://cdn.sheffield.ac.uk/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3NPhvqQHjM6Kpo.js?scope=footer&delta=0&language=en&theme=uos_public&include=eJxNjEEKgDAMBD9U7JNCm0ap1q7G5KCvFxHE28wchhcp1aCUmKGlosePhlHRTXoJ8-6iJ3ml5AbGujUxiX8JjoM2z61ynBpyauFyzTTCe0n2jN98A0vELbc urlProvider:network]] map[reflowTime:0.234 source:map[column:50393 line:2 type:source-location url:https://cdn.sheffield.ac.uk/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3NPhvqQHjM6Kpo.js?scope=footer&delta=0&language=en&theme=uos_public&include=eJxNjEEKgDAMBD9U7JNCm0ap1q7G5KCvFxHE28wchhcp1aCUmKGlosePhlHRTXoJ8-6iJ3ml5AbGujUxiX8JjoM2z61ynBpyauFyzTTCe0n2jN98A0vELbc urlProvider:network]] map[reflowTime:0.219 source:map[column:50457 line:2 type:source-location url:https://cdn.sheffield.ac.uk/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3NPhvqQHjM6Kpo.js?scope=footer&delta=0&language=en&theme=uos_public&include=eJxNjEEKgDAMBD9U7JNCm0ap1q7G5KCvFxHE28wchhcp1aCUmKGlosePhlHRTXoJ8-6iJ3ml5AbGujUxiX8JjoM2z61ynBpyauFyzTTCe0n2jN98A0vELbc 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.

	URL	Resource Size	Est Savings
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	95.8 KiB	81.8 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	81.6 KiB	67.5 KiB
Students on campus `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	56.3 KiB	40.7 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	48.5 KiB	35.3 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	47.8 KiB	34.7 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	36.1 KiB	26.3 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	35.3 KiB	25.7 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	33.8 KiB	24.6 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	33.3 KiB	24.2 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	30.9 KiB	22.5 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	26.5 KiB	19.3 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	26.4 KiB	19.2 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	24.0 KiB	17.5 KiB
div.media--image--figure > figure.imgcapt > picture > img `div.media--image--figure > figure.imgcapt > picture > img`	/sites/default/files/styles/mobile_single_column_2x/publi...	18.5 KiB	13.5 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-2-IMG

nodeLabel: Students on campus

path: 1,HTML,1,BODY,3,DIV,0,DIV,0,DIV,4,DIV,4,DIV,0,MAIN,2,SECTION,0,DIV,0,DIV,0,ARTICLE,0,DIV,2,DIV,0,DIV,1,DIV,0,DIV,0,FIGURE,0,PICTURE,4,IMG

selector: div.media--image--figure > figure.imgcapt > picture > img

snippet: <img loading="eager" width="375" height="211" src="https://sheffield.ac.uk/sites/default/files/styles/mobile_single_column_2x…" alt="Students on campus">

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.

URL	Protocol
sheffield.ac.uk/	http/1.1
sheffield.ac.uk/themes/custom/uos_public/images/logos/uos-crest.svg	http/1.1
/sites/default/files/styles/main_home/public/2026-03/Cove...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
/sites/default/files/styles/mobile_single_column_2x/publi...	http/1.1
sheffield.ac.uk/themes/custom/uos_public/favicon.svg	http/1.1
sheffield.ac.uk/themes/custom/uos_public/favicon.ico	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

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.

URL	Transfer Size	Duration
/consent/a3110129-5f04-4e81-9c5e-b494a7836315/OtAutoBlock.js	16.8 KiB	990 ms
cdn-ukwest.onetrust.com/scripttemplates/otSDKStub.js	9.1 KiB
/sites/default/files/css/css_w--SeWAlIkBVWx_reufqqGwWA9X_...	55.0 KiB	450 ms
/sites/default/files/css/css_LEqc-iG5QeVPDkBugYzgSyJGoZbo...	4.8 KiB	752 ms

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

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.

Estimated savings: 300 ms 69.6 KiB

URL	Transfer Size	Est Savings
/sites/default/files/css/css_w--SeWAlIkBVWx_reufqqGwWA9X_...	54.8 KiB	50.9 KiB
	21.2 KiB	18.7 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: 750 ms 141.2 KiB

URL	Transfer Size	Est Savings
/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3...	139.5 KiB	74.0 KiB
cdn-ukwest.onetrust.com/scripttemplates/202510.2.0/otBannerSdk.js	124.0 KiB	67.2 KiB

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Why this matters

Performance issues directly impact user engagement and conversion rates.

	URL
University of Sheffield homepage `div.logo > a > picture > img.resp`	sheffield.ac.uk/themes/custom/uos_public/images/logos/uos-crest.svg

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

●Layout shift culprits

●Document request latency

●Optimize DOM size

●LCP breakdown

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 1,971 KiB

●JavaScript execution time 0.6 s

●Minimizes main-thread work 1.4 s

●Avoid long main-thread tasks 4 long tasks found

●Page didn't prevent back/forward cache restoration

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 40 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Avoid multiple page redirects

●Initial server response time was short Root document took 40 ms

○INP breakdown

○User Timing marks and measures

○Avoid non-composited animations

○Avoid large layout shifts

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.

Navigation

Properly ordered headings that do not skip levels convey the semantic structure of the page, making it easier to navigate and understand when using assistive technologies. Learn more about heading order.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
The University of Sheffield `footer > div.row > div.large-9 > h4.footer-heading`

These are opportunities to improve keyboard navigation in your application.

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
Explore undergraduate study at Sheffield Make Sheffield the start of something… `div.block > div.row > div.medium-6 > a.signpost-card`
Search for a postgraduate course A masters from Sheffield means in-depth knowl… `div.block > div.row > div.medium-6 > a.signpost-card`
PhD study At Sheffield, you’ll join a supportive community of scholars who sha… `div.block > div.row > div.medium-4 > a.signpost-card`
Sheffield Live online events Our weekly online sessions help you find out abou… `div.block > div.row > div.medium-4 > a.signpost-card`
A world top-100 university We are proud to be recognised as one of the top 100… `div.row > div.medium-4 > div.block > a.signpost-card`
Research that changes lives Our centres of excellence are taking an interdisci… `div.block > div.row > div.medium-4 > a.signpost-card`
Our impact Our researchers are making life-changing discoveries and solving pr… `div.block > div.row > div.medium-4 > a.signpost-card`
Feed your curiosity The University of Sheffield Player is the place to discove… `div.block > div.row > div.medium-4 > a.signpost-card`
Defence Minister praises University of Sheffield’s role in supporting UK securi… `div.featured-news > div.views-element-container > div.newscard > a`
University of Sheffield students tackle overlooked women’s health crisis Urgen… `div.featured-news > div.views-element-container > div.newscard > a`
New life-giving brain cancer clinical trials to be offered to people in Sheffie… `div.featured-news > div.views-element-container > div.newscard > a`
UK’s first community-designed AI awareness campaign launched by University of S… `div.featured-news > div.views-element-container > div.newscard > a`

○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.

●Select elements have associated label elements.

●`[accesskey]` values are unique

●`button`, `link`, and `menuitem` elements have accessible names

●ARIA attributes are used as specified for the element's role

●Elements with `role="dialog"` or `role="alertdialog"` have accessible names.

●`[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.

●Document has a main landmark.

●Deprecated ARIA roles were not used

○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

○Links are distinguishable without relying on color.

○The document does not use `<meta http-equiv="refresh">`

○`<object>` elements have alternate text

○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>`.

○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.

Best Practices

General

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.

Source	Description
sheffield.ac.uk/	`Access to XMLHttpRequest at 'https://www.sheffield.ac.uk/nap/panel/menu' from origin 'https://sheffield.ac.uk' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.`
www.sheffield.ac.uk/nap/panel/menu	`Failed to load resource: net::ERR_FAILED`
/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3... line 120, col 12952	`Uncaught TypeError: $(...).once is not a function`
/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3... line 129, col 3638	`Uncaught TypeError: $(...).once is not a function`

Source maps translate minified code to the original source code. This helps developers debug in production. In addition, Lighthouse is able to provide further insights. Consider deploying source maps to take advantage of these benefits. Learn more about source maps.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL
/sites/default/files/js/js_jp6Lz0rnhBXaGt8cRu-KthubP_qJo3...

●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 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

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

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.

Crawling and Indexing

Search engines may use `href` attributes on links to crawl websites. Ensure that the `href` attribute of anchor elements links to an appropriate destination, so more pages of the site can be discovered. Learn how to make links crawlable

Why this matters

Performance issues directly impact user engagement and conversion rates.

Uncrawlable Link
Other ways to study `div.block > div.homecoursesearch > form.course-form > a.showotherways`

To appear in search results, crawlers need access to your app.

○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

●robots.txt is valid

●Image elements have `[alt]` attributes

●Document has a valid `hreflang`

●Document has a valid `rel=canonical`