Lighthouse Desktop

· 0 checks — Desktop 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.cookielaw.org/scripttemplates/202503.1.0/otBannerSdk.js	86400.0 s	115.9 KiB
platform.twitter.com/widgets.js	1800.0 s	27.3 KiB
www.kcl.ac.uk/image-library/press-photos/bush-house-view.jpg?f=webp	86400.0 s	35.5 KiB
/newimages/csss/website-images/research-2-Cropped-368x208...	86400.0 s	18.0 KiB
/departmentalimages/research/kings-doctoral-college-induc...	86400.0 s	17.6 KiB
cdn.cookielaw.org/consent/167b1744-c18f-47c4-bd0c-e8420eacd9e1/OtAutoBlock.js	86400.0 s	14.5 KiB
www.kcl.ac.uk/SiteElements/2017/images/international.png	86400.0 s	11.6 KiB
/newimages/strategy-2030/strategy-2030-hero-banner-robot-...	86400.0 s	11.4 KiB
cdn.cookielaw.org/scripttemplates/otSDKStub.js	86400.0 s	9.1 KiB
www.kcl.ac.uk/SiteElements/2017/images/postgraduate.png	86400.0 s	8.3 KiB
www.kcl.ac.uk/SiteElements/2017/images/laptop-thin-kcl-1.png	86400.0 s	8.2 KiB
/newimages/research/homepage/guys-cancer-centre-immunolog...	86400.0 s	7.6 KiB
www.kcl.ac.uk/SiteElements/2017/images/undergraduate.png	86400.0 s	7.6 KiB

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.

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
www.kcl.ac.uk/SiteElements/2017/fonts/KingsBureauGrotesqueFiveOne-woff.woff	60 ms
www.kcl.ac.uk/SiteElements/2017/fonts/kcl-icons-woff2.woff2?36ubot	60 ms
www.kcl.ac.uk/SiteElements/2017/fonts/KingsBureauGrotesqueThreeSeven-woff.woff	35 ms
www.kcl.ac.uk/SiteElements/2017/fonts/kcl-icons-ttf.ttf?36ubot	35 ms

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-0-DIV

nodeLabel: Shakespeare flat hero

path: 1,HTML,1,BODY,0,FORM,4,MAIN,1,DIV,0,DIV,5,SECTION,1,DIV,0,UL,2,LI,0,DIV,0,DIV

selector: ul#carousel-new__slides > li.glide__slide > div.carousel-new__img > div#shakespeares-missing-london-house-mapped-with-new-discovery-2

snippet: <div class="carousel-new__bg-img" id="shakespeares-missing-london-house-mapped-with-new-discovery-2" role="img" aria-label="Shakespeare flat hero" aria-role="presentation">

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.

URL	Transfer Size	Duration
www.kcl.ac.uk/siteelements/2017/js/glide.min.js	7.8 KiB
/SiteElements/2017/js/jquery-3.2.1.min.js?version=7389704...	30.6 KiB	141 ms
cdn.cookielaw.org/consent/167b1744-c18f-47c4-bd0c-e8420eacd9e1/OtAutoBlock.js	14.5 KiB	321 ms
/siteelements/2017/css/style.min.css?version=8013490?vers...	74.6 KiB	141 ms
cdn.cookielaw.org/scripttemplates/otSDKStub.js	9.1 KiB	57 ms

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
Woman in blue surgical scrubs looks at brains scans on a screen `div.col-12 > article.card > a.d-block > img.card-img-top`	/newimages/folsm/hero-banner/bmeis/bmeis-surgery.x0645e1a...	28.2 KiB	24.6 KiB
Book Launch_ A Research Agenda for Law, Finance and the Environment TN `div.col-12 > article.card > a.d-block > img.img-fluid`	/newimages/law/event-promos-780x440/book-launch-a-researc...	24.6 KiB	21.4 KiB
Jimmy Wales AI Leaders Event 780x440 `div.col-12 > article.card > a.d-block > img.img-fluid`	/newimages/ai/780x440/jimmy-wales-ai-leaders-event-780x44...	22.6 KiB	19.7 KiB
A person reading a menu at a restaurant `div.col-12 > article.card > a.d-block > img.card-img-top`	www.kcl.ac.uk/newimages/nmpc/calories.x84e42797.png?f=webp	19.9 KiB	17.4 KiB
JustEd `div.col-12 > article.card > a.d-block > img.img-fluid`	/newimages/sspp/ecs/events/justed.x805c9612.jpeg?w=1285&h...	19.2 KiB	16.7 KiB
A student standing on the roof deck of Bush House looking out over London. `section.container-fluid > div.row > div.col-12 > img.img-fluid`	www.kcl.ac.uk/image-library/press-photos/bush-house-view.jpg?f=webp	34.8 KiB	16.5 KiB
Partner with King's `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/newimages/csss/website-images/research-2-Cropped-368x208...	17.2 KiB	10.0 KiB
King's Doctoral College `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/departmentalimages/research/kings-doctoral-college-induc...	16.8 KiB	9.6 KiB
International students `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/international.png	10.8 KiB	8.3 KiB
Postgraduate taught `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/postgraduate.png	7.5 KiB	5.8 KiB
Postgraduate Research `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/laptop-thin-kcl-1.png	7.4 KiB	5.7 KiB
Undergraduate study `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/undergraduate.png	6.8 KiB	5.2 KiB
Invest in research and education excellence for a changing world `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/newimages/strategy-2030/strategy-2030-hero-banner-robot-...	10.6 KiB	4.5 KiB

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

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: 0.0 ms 66.8 KiB

URL	Transfer Size	Est Savings
/siteelements/2017/css/style.min.css?version=8013490?vers...	73.9 KiB	66.8 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: 120 ms 310.6 KiB

URL	Transfer Size	Est Savings
www.googletagmanager.com/gtag/js?id=G-1X78DS0GQQ&cx=c&gtm=4e64h1	169.1 KiB	111.5 KiB
cdn.cookielaw.org/scripttemplates/202503.1.0/otBannerSdk.js	115.8 KiB	69.7 KiB
www.googletagmanager.com/gtag/destination?id=G-1X78DS0GQQ&cx=c&gtm=4e64h1	169.2 KiB	66.7 KiB
www.googletagmanager.com/gtm.js?id=GTM-W5RSV5	191.7 KiB	62.6 KiB

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 reason	Failure type
Pages with cache-control:no-store header cannot enter back/forward cache.	Actionable
Pages whose main resource has cache-control:no-store cannot enter back/forward cache.	Not actionable
Back/forward cache is disabled because some JavaScript network request received resource with Cache-Control: no-store header.	Not actionable

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
A student standing on the roof deck of Bush House looking out over London. `section.container-fluid > div.row > div.col-12 > img.img-fluid`	www.kcl.ac.uk/image-library/press-photos/bush-house-view.jpg?f=webp
Postgraduate taught `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/postgraduate.png
International students `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/international.png
Undergraduate study `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/undergraduate.png
Postgraduate Research `div.row > div.col-6 > article.block--study-new__course > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/laptop-thin-kcl-1.png
Invest in research and education excellence for a changing world `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/newimages/strategy-2030/strategy-2030-hero-banner-robot-...
Partner with King's `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/newimages/csss/website-images/research-2-Cropped-368x208...
Research impact `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/newimages/research/homepage/guys-cancer-centre-immunolog...
King's Doctoral College `div.col-xs-12 > article.card > a.d-block > img.img-fluid`	/departmentalimages/research/kings-doctoral-college-induc...
King's College London `div.col-12 > div.footer__item > a > img.img-fluid`	www.kcl.ac.uk/SiteElements/2017/images/kcl-logo.svg

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: 601 ms

URL	Time Spent
kcl.ac.uk/	281 ms
www.kcl.ac.uk/	321 ms
www.kcl.ac.uk/	0.0 ms

●Time to Interactive 2.2 s

●Max Potential First Input Delay 70 ms

●Layout shift culprits

●Optimize DOM size

●Forced reflow

●LCP breakdown

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●Avoids enormous network payloads Total size was 1,451 KiB

●User Timing marks and measures 7 user timings

●JavaScript execution time 0.2 s

●Minimizes main-thread work 0.5 s

●Avoid long main-thread tasks 1 long task found

●Network Requests

●Network Round Trip Times 30 ms

●Server Backend Latencies 30 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 60 ms

○INP breakdown

○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.

ARIA

Assistive technologies, like screen readers, can't interpret ARIA attributes with invalid names. Learn more about valid ARIA attributes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Shakespeare flat hero `ul#carousel-new__slides > li.glide__slide > div.carousel-new__img > div#shakespeares-missing-london-house-mapped-with-new-discovery-2`
two students chatting at an open evening `ul#carousel-new__slides > li.glide__slide > div.carousel-new__img > div#postgraduate-taught-events`

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.

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
Undergraduate `div.row > div.col-6 > article.block--study-new__course > h3`

These are opportunities to improve keyboard navigation in your application.

○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]`s are contained by their required parent element

●`[role]` values are valid

●`[aria-*]` attributes have valid values

●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.

●`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.

●Skip links are focusable.

●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 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

○Select elements have associated label elements.

○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

Trust and Safety

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being served over HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more about HTTPS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Insecure URL	Request Resolution
www.kcl.ac.uk/	Allowed

●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

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 are unable to include your pages in search results if they don't have permission to crawl them. Learn more about crawler directives.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Blocking Directive Source
`x-robots-tag: noindex`

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

○Structured data is valid

●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`