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
www.edx.org/api/auto-block?id=fa169e97-be64-4cc1-bad3-9534590f9a30	3600.0 s	93.4 KiB
/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fattac...	300.0 s	57.9 KiB
beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js	86400.0 s	110.5 KiB
www.edx.org/beam.js	0.0 ms	35.1 KiB
/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fattac...	300.0 s	18.6 KiB
www.edx.org/favicon.ico	300.0 s	10.1 KiB
sonic-ui.highereducation.com/latest/ucl.adapter.js	86400.0 s	21.2 KiB
beam.edx.org/scripttemplates/otSDKStub.js	86400.0 s	9.3 KiB
www.edx.org/trademark-logos/edx-by-2u-white.svg	10.0 s	2.8 KiB
www.edx.org/trademark-logos/edx-logo-elm.svg	10.0 s	2.6 KiB
edx-cdn.org/v3/prod/logo.svg	3600.0 s	2.4 KiB
sonic-ui.highereducation.com/latest/ucl.publisher.js	86400.0 s	4.7 KiB
www.edx.org/_next/image?url=%2Ficons%2Fai-icon.png&w=96&q=75	300.0 s	1.8 KiB
/_r?sdk=web2.86.4&branch_key=key_live_kpxBY7wsvq7tp8eu5TH...	0.0 ms	672 B
beam.edx.org/logos/static/ot_close.svg	86400.0 s	1.1 KiB

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:0.024575] map[node:map[boundingRect:map[bottom:2326 height:668 left:0 right:412 top:1658 width:412] lhId:page-1-DIV nodeLabel:Trending on edX Executive Education Featured AI & Digital Transformation Sustai… path:1,HTML,1,BODY,4,DIV,1,MAIN,0,ARTICLE,2,DIV selector:div > main#page-id-3021 > article.container > div.py-8 snippet:<div class="py-8 lg:py-20 mx-break-out flex justify-center bg-putty-100"> type:node] score:0.024575]]

items: [map[node:map[type:text value:Total] score:0.016437] map[node:map[boundingRect:map[bottom:823 height:307 left:0 right:412 top:516 width:412] lhId:page-4-DIV nodeLabel:We and our partners use cookies to enhance your experience on our site, analyse… path:1,HTML,1,BODY,317,DIV,1,DIV selector:body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk snippet:<div id="onetrust-banner-sdk" class="otFlat bottom ot-wo-title ot-buttons-fw" tabindex="0" role="region" aria-label="Cookie banner" style="bottom: 0px;"> type:node] score:0.006723] map[node:map[boundingRect:map[bottom:823 height:76 left:0 right:412 top:747 width:412] lhId:page-3-IFRAME nodeLabel:Branch Banner Frame path:1,HTML,1,BODY,0,IFRAME selector:body.__className_f367f3 > iframe#branch-banner-iframe snippet:<iframe src="about:blank" scrolling="no" id="branch-banner-iframe" class="branch-animation" aria-label="Branch Banner Frame" style="overflow: hidden; bottom: 0px;"> type:node] score:0.004606] map[node:map[boundingRect:map[bottom:823 height:76 left:0 right:412 top:747 width:412] lhId:page-3-IFRAME nodeLabel:Branch Banner Frame path:1,HTML,1,BODY,0,IFRAME selector:body.__className_f367f3 > iframe#branch-banner-iframe snippet:<iframe src="about:blank" scrolling="no" id="branch-banner-iframe" class="branch-animation" aria-label="Branch Banner Frame" style="overflow: hidden; bottom: 0px;"> type:node] score:0.002818] map[node:map[boundingRect:map[bottom:823 height:307 left:0 right:412 top:516 width:412] lhId:page-4-DIV nodeLabel:We and our partners use cookies to enhance your experience on our site, analyse… path:1,HTML,1,BODY,317,DIV,1,DIV selector:body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk snippet:<div id="onetrust-banner-sdk" class="otFlat bottom ot-wo-title ot-buttons-fw" tabindex="0" role="region" aria-label="Cookie banner" style="bottom: 0px;"> type:node] score:0.001156] map[node:map[boundingRect:map[bottom:823 height:307 left:0 right:412 top:516 width:412] lhId:page-4-DIV nodeLabel:We and our partners use cookies to enhance your experience on our site, analyse… path:1,HTML,1,BODY,317,DIV,1,DIV selector:body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk snippet:<div id="onetrust-banner-sdk" class="otFlat bottom ot-wo-title ot-buttons-fw" tabindex="0" role="region" aria-label="Cookie banner" style="bottom: 0px;"> type:node] score:0.001134]]

items: [map[node:map[type:text value:Total] score:0.035997] map[node:map[boundingRect:map[bottom:823 height:307 left:0 right:412 top:516 width:412] lhId:page-4-DIV nodeLabel:We and our partners use cookies to enhance your experience on our site, analyse… path:1,HTML,1,BODY,317,DIV,1,DIV selector:body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk snippet:<div id="onetrust-banner-sdk" class="otFlat bottom ot-wo-title ot-buttons-fw" tabindex="0" role="region" aria-label="Cookie banner" style="bottom: 0px;"> type:node] score:0.035997]]

items: [map[node:map[type:text value:Total] score:0.167697] map[node:map[boundingRect:map[bottom:1658 height:120 left:16 right:396 top:1538 width:380] lhId:page-5-DIV nodeLabel:Next slide path:1,HTML,1,BODY,4,DIV,1,MAIN,0,ARTICLE,1,DIV selector:div > main#page-id-3021 > article.container > div.py-1 snippet:<div class="py-1"> type:node] score:0.167697]]

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:118.354 source:map[column:51496 line:1 type:source-location url:https://www.edx.org/_next/static/chunks/31684-c747813ca79ce5e5.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:5.179 source:map[column:60234 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/94285-58c8714c348a9f22.js urlProvider:network]] map[reflowTime:41.311 source:map[column:302174 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/34713-2dc09c03d2c34781.js urlProvider:network]] map[reflowTime:55.097 source:map[type:text value:[unattributed]]] map[reflowTime:1.333 source:map[column:19436 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/45618.b1cc06f52ae589f0.js urlProvider:network]] map[reflowTime:4.178 source:map[column:40384 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/45618.b1cc06f52ae589f0.js urlProvider:network]] map[reflowTime:1.828 source:map[column:332 line:412 type:source-location url:https://www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js urlProvider:network]] map[reflowTime:0.648 source:map[column:55 line:936 type:source-location url:https://www.googletagmanager.com/gtag/js?id=G-D3KS4KMDT0&cx=c&gtm=4e64e1 urlProvider:network]] map[reflowTime:26.001 source:map[column:260578 line:6 type:source-location url:https://beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js urlProvider:network]] map[reflowTime:1.207 source:map[column:39959 line:6 type:source-location url:https://beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js urlProvider:network]] map[reflowTime:10.285 source:map[column:148983 line:6 type:source-location url:https://beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js urlProvider:network]] map[reflowTime:88.52 source:map[column:17508 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/58355-0a989aab31f5c1e2.js urlProvider:network]] map[reflowTime:24.921 source:map[column:17570 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/13542-c6a4f9991134f550.js urlProvider:network]] map[reflowTime:0.891 source:map[column:314061 line:0 type:source-location url:https://www.edx.org/_next/static/chunks/34713-2dc09c03d2c34781.js urlProvider:network]]]

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:634.9370001220703 label:Time to first byte subpart:timeToFirstByte] map[duration:11249.98199987793 label:Resource load delay subpart:resourceLoadDelay] map[duration:59.12 label:Resource load duration subpart:resourceLoadDuration] map[duration:38.572 label:Element render delay subpart:elementRenderDelay]]

lhId: page-0-IMG

nodeLabel: div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001

path: 1,HTML,1,BODY,4,DIV,1,MAIN,0,ARTICLE,0,DIV,1,DIV,0,DIV,0,DIV,0,DIV,0,IMG

selector: div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001

snippet: <img alt="" data-ot-ignore="" fetchpriority="high" loading="lazy" decoding="async" data-nimg="fill" class="optanon-category-C0001 object-cover object-right relative z-[-1] m-0 sm:hi…" sizes="100vw" srcset="/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fattachment-27642Backgr…" src="https://www.edx.org/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fatt…" style="position: absolute; height: 100%; width: 100%; inset: 0px;">

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-IMG

nodeLabel: div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001

path: 1,HTML,1,BODY,4,DIV,1,MAIN,0,ARTICLE,0,DIV,1,DIV,0,DIV,0,DIV,0,DIV,0,IMG

selector: div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001

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
www.edx.org/_next/static/css/1e97b410b545a5d8.css	6.7 KiB	151 ms
www.edx.org/_next/static/css/5e9f44976815350e.css	5.8 KiB
www.edx.org/_next/static/css/838d848756a3dba0.css	1.3 KiB
www.edx.org/_next/static/css/b7125049fdf54480.css	1.5 KiB
www.edx.org/_next/static/css/619a486fdabe4db9.css	1.9 KiB
www.edx.org/_next/static/css/622ea16a66844b51.css	3.0 KiB
www.edx.org/_next/static/css/7201a3f57b93e520.css	2.4 KiB

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.container > div.lg:ml-auto > div.w-full > img.optanon-category-C0001 `div.container > div.lg:ml-auto > div.w-full > img.optanon-category-C0001`	/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fattac...	56.7 KiB	38.7 KiB
AI for Everyone: Master the Basics `a.w-full > div.text-card-foreground > div.flex > img.optanon-category-C0001`	/_next/image?url=https%3A%2F%2Fprod-discovery.edx-cdn.org...	41.2 KiB	21.6 KiB
Supply Chain Fundamentals. `a.w-full > div.text-card-foreground > div.flex > img.optanon-category-C0001`	/_next/image?url=https%3A%2F%2Fprod-discovery.edx-cdn.org...	28.0 KiB	8.4 KiB
div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001 `div.embla__container > div.embla__slide > div.relative > img.optanon-category-C0001`	/_next/image?url=https%3A%2F%2Fimages.cdn.edx.org%2Fattac...	17.5 KiB	5.9 KiB

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.

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: 754 ms

URL	Time Spent
edx.org/	754 ms
www.edx.org/	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.

Element	Layout shift score
Next slide `div > main#page-id-3021 > article.container > div.py-1`	0.168
We and our partners use cookies to enhance your experience on our site, analyse… `body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk`	0.036
Trending on edX Executive Education Featured AI & Digital Transformation Sustai… `div > main#page-id-3021 > article.container > div.py-8`	0.025
We and our partners use cookies to enhance your experience on our site, analyse… `body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk`	0.007
Branch Banner Frame `body.__className_f367f3 > iframe#branch-banner-iframe`	0.005
Branch Banner Frame `body.__className_f367f3 > iframe#branch-banner-iframe`	0.003
We and our partners use cookies to enhance your experience on our site, analyse… `body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk`	0.001
We and our partners use cookies to enhance your experience on our site, analyse… `body.__className_f367f3 > div#onetrust-consent-sdk > div#onetrust-banner-sdk`	0.001

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: 2.0 s 391.6 KiB

URL	Transfer Size	Est Savings
www.edx.org/_next/static/css/c1a0daa9433fa738.css	307.5 KiB	305.5 KiB
www.edx.org/_next/static/css/8d3c32105a4dd1a6.css	72.3 KiB	72.2 KiB
www.edx.org/_next/static/css/e5fec6745b51671e.css	13.9 KiB	13.9 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: 11.1 s 1.8 MiB

URL	Transfer Size	Est Savings
www.edx.org/_next/static/chunks/77035-cd6004d04665d287.js	560.3 KiB	448.7 KiB
www.edx.org/_next/static/chunks/82c1a80d-ae299923ae10f5b2.js	226.0 KiB	191.0 KiB
www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js	361.8 KiB	177.0 KiB
www.edx.org/_next/static/chunks/4cde4f2d-a6ae58bcb4c8999f.js	143.3 KiB	141.5 KiB
www.edx.org/_next/static/chunks/a4634e51-e0ea9966714daeda.js	117.9 KiB	112.3 KiB
www.googletagmanager.com/gtm.js?id=GTM-543ZGMK2	166.1 KiB	79.7 KiB
www.edx.org/_next/static/chunks/aaea2bcf-fcf14465037c204e.js	99.3 KiB	70.2 KiB
www.googletagmanager.com/gtag/js?id=G-D3KS4KMDT0&cx=c&gtm=4e64e1	179.8 KiB	68.2 KiB
beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js	109.7 KiB	66.2 KiB
www.edx.org/_next/static/chunks/34713-2dc09c03d2c34781.js	93.3 KiB	62.2 KiB
www.edx.org/_next/static/chunks/10c000c1-820b48e60ecf9a58.js	55.7 KiB	55.6 KiB
www.edx.org/_next/static/chunks/4a5bd2f9-11d23ed2fab7c94c.js	61.2 KiB	54.7 KiB
www.edx.org/_next/static/chunks/ae064d6e-be7bdf3c6845b5d3.js	58.6 KiB	53.7 KiB
www.edx.org/_next/static/chunks/18192-00429a85436192b6.js	68.7 KiB	46.7 KiB
www.edx.org/_next/static/chunks/56827-2aa3be22f6d464ca.js	64.4 KiB	41.8 KiB
www.edx.org/_next/static/chunks/b8ba6eb2-3ac6594aa448865d.js	51.3 KiB	39.5 KiB
www.edx.org/_next/static/chunks/6150e6b2-d454fae9bf4565bd.js	47.8 KiB	33.8 KiB
www.edx.org/_next/static/chunks/94466-1f4eaaf7e4c46361.js	47.7 KiB	24.8 KiB
www.edx.org/_next/static/chunks/d648eb28-f98479d2cde4bc66.js	24.3 KiB	21.6 KiB
www.edx.org/_next/static/chunks/8cc6faea-d4a5213af5d556c9.js	25.6 KiB	20.9 KiB
www.edx.org/_next/static/chunks/68097-7170da9a8c8e222a.js	22.8 KiB	20.4 KiB

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.

URL	Total CPU Time	Script Evaluation	Script Parse
www.edx.org/_next/static/chunks/31684-c747813ca79ce5e5.js	27.2 s	25.9 s	26 ms
www.edx.org/	6.5 s	1.2 s	607 ms
Unattributable	1.9 s	89 ms	0.0 ms
www.edx.org/_next/static/chunks/77035-cd6004d04665d287.js	1.7 s	1.4 s	290 ms
www.edx.org/_next/static/chunks/4bd1b696-8114277e1a0c5c1d.js	1.4 s	1.0 s	53 ms
www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js	927 ms	634 ms	142 ms
www.googletagmanager.com/gtag/js?id=G-D3KS4KMDT0&cx=c&gtm=4e64e1	768 ms	553 ms	98 ms
www.googletagmanager.com/gtm.js?id=GTM-543ZGMK2	701 ms	604 ms	84 ms
www.edx.org/_next/static/css/c1a0daa9433fa738.css	584 ms	0.0 ms	0.0 ms
beam.edx.org/scripttemplates/202407.2.0/otBannerSdk.js	472 ms	230 ms	80 ms
www.edx.org/beam.js	362 ms	319 ms	21 ms
js-agent.newrelic.com/nr-spa-1.312.1.min.js	334 ms	270 ms	20 ms
www.edx.org/api/auto-block?id=fa169e97-be64-4cc1-bad3-9534590f9a30	286 ms	131 ms	130 ms
www.edx.org/_next/static/chunks/21307-8f0e72a894fab571.js	284 ms	280 ms	2.9 ms
www.edx.org/_next/static/chunks/34713-2dc09c03d2c34781.js	202 ms	19 ms	60 ms
www.edx.org/_next/static/chunks/45618.b1cc06f52ae589f0.js	174 ms	113 ms	14 ms
www.edx.org/_next/static/chunks/82c1a80d-ae299923ae10f5b2.js	113 ms	1.1 ms	111 ms
beam.edx.org/scripttemplates/otSDKStub.js	96 ms	73 ms	5.4 ms
www.edx.org/_next/static/chunks/43145-424523c8bdc43658.js	89 ms	83 ms	6.2 ms
sonic-ui.highereducation.com/latest/ucl.adapter.js	84 ms	30 ms	52 ms
www.edx.org/_next/static/chunks/10c000c1-820b48e60ecf9a58.js	67 ms	1.1 ms	65 ms
www.edx.org/_next/static/chunks/a4634e51-e0ea9966714daeda.js	58 ms	1.0 ms	57 ms
www.edx.org/_next/static/chunks/4cde4f2d-a6ae58bcb4c8999f.js	58 ms	0.9 ms	56 ms
/_r?sdk=web2.86.4&branch_key=key_live_kpxBY7wsvq7tp8eu5TH...	54 ms	41 ms	0.5 ms
www.edx.org/_next/static/chunks/94285-58c8714c348a9f22.js	50 ms	13 ms	10 ms

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.

Category	Time Spent
Script Evaluation	33.4 s
Other	5.0 s
Script Parsing & Compilation	2.4 s
Style & Layout	2.1 s
Parse HTML & CSS	1.2 s
Garbage Collection	815 ms
Rendering	422 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 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

Large network payloads cost users real money and are highly correlated with long load times. Learn how to reduce payload sizes.

Why this matters

Performance issues directly impact user engagement and conversion rates.

URL	Transfer Size
www.edx.org/_next/static/chunks/77035-cd6004d04665d287.js	563.2 KiB
www.edx.org/	516.9 KiB
www.edx.org/	458.4 KiB
www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js	362.3 KiB
www.gstatic.com/recaptcha/releases/gTpTIWhbKpxADzTzkcabhXN4/recaptcha__en.js	361.9 KiB
www.edx.org/_next/static/css/c1a0daa9433fa738.css	308.5 KiB
www.edx.org/_next/static/chunks/82c1a80d-ae299923ae10f5b2.js	227.0 KiB
www.googletagmanager.com/gtag/js?id=G-D3KS4KMDT0&cx=c&gtm=4e64e1	179.9 KiB
www.googletagmanager.com/gtm.js?id=GTM-543ZGMK2	166.4 KiB
www.edx.org/_next/static/chunks/4cde4f2d-a6ae58bcb4c8999f.js	144.3 KiB

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

●Optimize DOM size

●Font display

●Modern HTTP

●Optimize viewport for mobile

●Minify CSS

●Minify JavaScript

●User Timing marks and measures 5 user timings

●Avoid long main-thread tasks 20 long tasks found

●Avoid non-composited animations 2 animated elements found

●Image elements have explicit `width` and `height`

●Network Requests

●Network Round Trip Times 90 ms

●Server Backend Latencies 280 ms

●Tasks

●Diagnostics

●Metrics

●Screenshot Thumbnails

●Final Screenshot

●Script Treemap Data

●Resources Summary

●Initial server response time was short Root document took 50 ms

○INP breakdown

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. Learn how to provide sufficient color contrast.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
Decline Optional Cookies `div.ot-sdk-row > div#onetrust-button-group-parent > div#onetrust-button-group > button#onetrust-reject-all-handler`
Accept All Cookies `div.ot-sdk-row > div#onetrust-button-group-parent > div#onetrust-button-group > button#onetrust-accept-btn-handler`

These are opportunities to improve the legibility of your content.

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
Computer Science `div.text-base > div.flex > a.no-underline > h4.elm-h5`

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
Cookie Policy `div#onetrust-group-container > div#onetrust-policy > div#onetrust-policy-text > a.ot-cookie-policy-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]`s are contained by their required parent element

●`[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

●`[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.

●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

●Document has a `<title>` element

●`<frame>` or `<iframe>` elements have a title

●`<html>` element has a `[lang]` attribute

●`<html>` element has a valid value for its `[lang]` attribute

●Links are distinguishable without relying on color.

●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 IDs are unique

●All heading elements contain content.

○`[accesskey]` values are unique

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

○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

○No form fields have multiple labels

○`<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

○Form elements have associated labels

○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>`.

○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
courses.edx.org/login_refresh	`Failed to load resource: the server responded with a status of 401 ()`
courses.edx.org/login_refresh	`Failed to load resource: the server responded with a status of 401 ()`

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.

●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

○Redirects HTTP traffic to HTTPS

○Mitigate clickjacking with XFO or CSP

○Detected JavaScript libraries

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.

Content Best Practices

Descriptive link text helps search engines understand your content. Learn how to make links more accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Link destination	Link Text
www.edx.org/courses-and-programs-promo	Learn more
www.edx.org/courses-and-programs-promo	Learn more
www.edx.org/courses-and-programs-promo	Learn more
www.edx.org/courses-and-programs-promo	Learn more

Format your HTML in a way that enables crawlers to better understand your app’s content.

○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 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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