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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.

90

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
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg0.0 ms4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg0.0 ms2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg0.0 ms2.0 MiB
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg0.0 ms2.0 MiB
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png0.0 ms1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg0.0 ms1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg0.0 ms1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg0.0 ms1.2 MiB
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.png0.0 ms697.4 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg0.0 ms567.5 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png0.0 ms543.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png0.0 ms528.9 KiB
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg0.0 ms312.4 KiB
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg0.0 ms232.3 KiB
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpg0.0 ms209.0 KiB
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpg0.0 ms178.0 KiB
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg0.0 ms166.9 KiB
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg0.0 ms158.7 KiB
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg0.0 ms155.7 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpg0.0 ms144.7 KiB
www.pku.edu.cn/Public/static/themes/image/pic65.jpg0.0 ms132.5 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg0.0 ms125.3 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png0.0 ms50.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpg0.0 ms47.4 KiB
www.pku.edu.cn/Public/static/themes/image/png92.png0.0 ms44.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg0.0 ms41.4 KiB
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff0.0 ms39.9 KiB
www.pku.edu.cn/Public/static/themes/image/png96.png0.0 ms35.1 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.js0.0 ms33.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png0.0 ms28.6 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg0.0 ms27.2 KiB
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg0.0 ms23.8 KiB
www.pku.edu.cn/Public/static/themes/image/bg8.png0.0 ms23.8 KiB
www.pku.edu.cn/Public/static/themes/css/global.css0.0 ms22.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js0.0 ms22.2 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png0.0 ms18.0 KiB
www.pku.edu.cn/Public/static/themes/image/bg9a.svg0.0 ms16.9 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js0.0 ms15.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpg0.0 ms14.7 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js0.0 ms12.8 KiB
www.pku.edu.cn/Public/static/themes/css/fix.css0.0 ms11.0 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpg0.0 ms10.3 KiB
www.pku.edu.cn/Public/static/themes/image/png27.png0.0 ms9.5 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpg0.0 ms9.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js0.0 ms8.7 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpg0.0 ms7.8 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpg0.0 ms7.1 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.png0.0 ms6.7 KiB
www.pku.edu.cn/Public/static/themes/js/fun.js0.0 ms5.9 KiB
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpg0.0 ms5.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js0.0 ms4.8 KiB
www.pku.edu.cn/Public/static/themes/image/png25.png0.0 ms4.4 KiB
/collector/statistic.js?channelId=&channelName=&articleId...0.0 ms3.5 KiB
www.pku.edu.cn/Public/static/themes/image/png26.png0.0 ms2.9 KiB
www.pku.edu.cn/Public/static/themes/js/global.js0.0 ms2.8 KiB
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css0.0 ms2.7 KiB
www.pku.edu.cn/Public/static/themes/image/png23.png0.0 ms2.4 KiB
www.pku.edu.cn/Public/static/themes/js/homeJson.js0.0 ms2.2 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.js0.0 ms2.0 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js0.0 ms1.8 KiB
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js0.0 ms1.7 KiB
www.pku.edu.cn/Public/static/themes/image/png34.png0.0 ms1.6 KiB
www.pku.edu.cn/Public/static/themes/image/png32.svg0.0 ms1.3 KiB
www.pku.edu.cn/Public/static/themes/image/more1a.svg0.0 ms1.3 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/image/more1b.svg0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/image/more1.svg0.0 ms1.2 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js0.0 ms1.1 KiB
www.pku.edu.cn/Public/static/themes/css/slick.css0.0 ms848 B
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg0.0 ms0 B

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.

URLEst Savings
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woff270 ms

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:1100.524 label:Time to first byte subpart:timeToFirstByte] map[duration:1475.502 label:Element render delay subpart:elementRenderDelay]]
lhId: page-0-DIV
nodeLabel: 北京大学校园开放日暨本科招生宣讲会
path: 2,HTML,1,BODY,7,DIV,2,DIV,0,DIV,0,DIV,0,DIV,1,DIV,0,DIV,0,DIV,1,DIV
selector: div#slick-slide00 > div > div.child > div.fz30
snippet: <div class="fz30">

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

URLProtocol
www.pku.edu.cn/http/1.1
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/global.csshttp/1.1
www.pku.edu.cn/Public/static/themes/css/fix.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.easing.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/global.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/fun.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/vivus.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/iscroll.jshttp/1.1
www.pku.edu.cn/Public/static/themes/css/slick.csshttp/1.1
www.pku.edu.cn/Public/static/themes/js/slick.jshttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/08/s5decd8b95f388.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/pic65.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/js/homeJson.jshttp/1.1
www.pku.edu.cn/Public/static/themes/js/plus/jquery.imgpreload.jshttp/1.1
www.pku.edu.cn/Public/static/themes/image/png96.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/css/fonts/iconfont.woffhttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png27.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png23.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1a.svghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58ada3ef15.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b3611072.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58b7aaab99.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/03/s5de58bbebf671.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c77d7a66e70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1b.svghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/20/s5dfc40dc928fb.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2025/09/17/s68ca4cd3c10bb.pnghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa062371400.jpghttp/1.1
www.pku.edu.cn/Uploads/Picture/2019/12/18/s5dfa063869f70.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png32.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png25.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png26.pnghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png34.pnghttp/1.1
www.pku.edu.cn/dat/recentList.xmlhttp/1.1
www.pku.edu.cn/dat/recentStatement.xmlhttp/1.1
www.pku.edu.cn/dat/topNews.jsonhttp/1.1
www.pku.edu.cn/dat/imgNews.jsonhttp/1.1
www.pku.edu.cn/dat/teachResearchNews.jsonhttp/1.1
www.pku.edu.cn/dat/mediaPKU.jsonhttp/1.1
www.pku.edu.cn/dat/forumPKU.jsonhttp/1.1
www.pku.edu.cn/dat/pkuPeople.jsonhttp/1.1
www.pku.edu.cn/dat/hotTopics.jsonhttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg9a.svghttp/1.1
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpghttp/1.1
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpghttp/1.1
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeghttp/1.1
www.pku.edu.cn/Public/static/themes/image/png92.pnghttp/1.1
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeghttp/1.1
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeghttp/1.1
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpghttp/1.1
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.pnghttp/1.1
www.pku.edu.cn/dat/img/6c7b130555df477791adf7fa0d08e4bf.jpghttp/1.1
www.pku.edu.cn/dat/img/3f24a9b3793f4520ae77c2d405badf92.jpghttp/1.1
www.pku.edu.cn/Public/static/themes/image/more1.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg14.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg5.svghttp/1.1
www.pku.edu.cn/Public/static/themes/image/bg8.pnghttp/1.1

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

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

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.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js22.2 KiB127 ms
www.pku.edu.cn/Public/static/themes/js/slick.js15.7 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.8 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.7 KiB87 ms
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.8 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mChange.js1.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.js33.1 KiB287 ms
www.pku.edu.cn/Public/static/themes/js/plus/old/winscreen.js1.7 KiB
www.pku.edu.cn/Public/static/themes/js/fun.js5.9 KiB
www.pku.edu.cn/Public/static/themes/js/global.js2.8 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.mousewheel.js1.1 KiB
www.pku.edu.cn/Public/static/themes/js/jquery.easing.js1.2 KiB127 ms
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB207 ms
www.pku.edu.cn/Public/static/themes/css/slick.css848 B127 ms
www.pku.edu.cn/Public/static/themes/css/fix.css11.0 KiB127 ms
www.pku.edu.cn/Public/static/themes/css/jquery.mCustomScrollbar.css2.7 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.

URLResource SizeEst Savings
我国科学家近日在光通信和6G领域取得突破性进展 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB2.8 MiB
北京大学2025-2026学年“应乐而声”校园十佳歌手大赛总决赛举行 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg2.0 MiB1.7 MiB
北京大学区域与国别研究院建院八周年 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB1.1 MiB
全球首个靶向整合素的创新核药获批上市 北大为中国核医学70周年献礼 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB820.5 KiB
北京大学校园开放日暨本科招生宣讲会 div.slick-track > div.slick-slide > div > div.child
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB747.5 KiB
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png28.3 KiB26.8 KiB
body > div.body_home > div.rr body > div.body_home > div.rr
www.pku.edu.cn/Public/static/themes/image/png27.png9.2 KiB6.9 KiB

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

Diagnostics

Minifying CSS files can reduce network payload sizes. Learn how to minify CSS.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Estimated savings: 0.0 ms 2.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.8 KiB2.1 KiB

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: 0.0 ms 24.1 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/js/jquery.mCustomScrollbar.js21.8 KiB8.5 KiB
www.pku.edu.cn/Public/static/themes/js/slick.js15.3 KiB6.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/vivus.js8.4 KiB4.3 KiB
www.pku.edu.cn/Public/static/themes/js/iscroll.js12.4 KiB3.1 KiB
www.pku.edu.cn/Public/static/themes/js/plus/jquery.mScroll.js4.5 KiB2.0 KiB

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 26.6 KiB
URLTransfer SizeEst Savings
www.pku.edu.cn/Public/static/themes/css/global.css22.5 KiB16.2 KiB
www.pku.edu.cn/Public/static/themes/css/fix.css10.7 KiB10.4 KiB

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.

URLTransfer Size
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d1418721.jpg4.1 MiB
www.pku.edu.cn/dat/img/fe7afc17eccc47c499adca9b6c549b4e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/02/s69cdfe602790e.jpg2.1 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/17/s69e1c2a2f1019.jpg2.0 MiB
www.pku.edu.cn/Uploads/Picture/2026/03/31/s69cb7d26ba8a5.jpg2.0 MiB
www.pku.edu.cn/dat/img/b2080858ec064a049de34c1ca7eb81e9.png1.9 MiB
www.pku.edu.cn/Uploads/Picture/2026/04/09/s69d759af9ca1b.jpg1.4 MiB
www.pku.edu.cn/Uploads/Picture/2026/02/27/s69a0fec9dcf3b.jpg1.3 MiB
www.pku.edu.cn/dat/img/344b546ab3de42e885101859f6b8ed3b.jpg1.2 MiB
www.pku.edu.cn/dat/img/7fc4f699f7bc45f39f49c2d2d292bc1c.jpg1.0 MiB

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

Why this matters

Performance issues directly impact user engagement and conversion rates.

CategoryTime Spent
Other1.5 s
Style & Layout643 ms
Rendering559 ms
Script Evaluation258 ms
Garbage Collection20 ms
Parse HTML & CSS18 ms
Script Parsing & Compilation14 ms

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
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/15e75d5f2c624be9a8cf1374c317fcf4.jpeg
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/31/s5e0aa9359ae68.png
div.pic > div.img > a > img div.pic > div.img > a > img
www.pku.edu.cn/dat/img/4bdf82f5e8a24fcc9b4e108f570f317a.jpeg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/22/s68d10dcacb977.jpg
div.inner > div.l > a > img div.inner > div.l > a > img
www.pku.edu.cn/dat/img/85d41f2c3212461b885294a7d7d996b3.jpeg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6ab0f45e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/08/s68beb6392fd51.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2024/11/06/s672b1d5a8248e.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/02/s6362348db2897.png
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2025/09/15/s68c789787fad6.jpg
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04147ee4a83.png
div.block > div.logo > a > img div.block > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png
div.inner > div.logo > a > img div.inner > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/26/s5e04176fbbfa3.png
div.share-box > a.share-item > span.code > img div.share-box > a.share-item > span.code > img
www.pku.edu.cn/Uploads/Picture/2019/12/27/s5e05ab4267239.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg
div.item > div.l > div.pic > img div.item > div.l > div.pic > img
www.pku.edu.cn/Uploads/Picture/2022/11/22/s637cb8c134d80.jpg
div.part2 > div.logo > a > img div.part2 > div.logo > a > img
www.pku.edu.cn/Uploads/Picture/2019/12/05/s5de8762313bab.png
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div > div.child > a > img._lazyload div > div.child > a > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide20 > div > div.child > img._lazyload div#slick-slide20 > div > div.child > img._lazyload
div#slick-slide21 > div > div.child > img._lazyload div#slick-slide21 > div > div.child > img._lazyload
div#slick-slide22 > div > div.child > img._lazyload div#slick-slide22 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div#slick-slide30 > div > div.child > img._lazyload div#slick-slide30 > div > div.child > img._lazyload
div#slick-slide31 > div > div.child > img._lazyload div#slick-slide31 > div > div.child > img._lazyload
div#slick-slide32 > div > div.child > img._lazyload div#slick-slide32 > div > div.child > img._lazyload
div#slick-slide33 > div > div.child > img._lazyload div#slick-slide33 > div > div.child > img._lazyload
div#slick-slide34 > div > div.child > img._lazyload div#slick-slide34 > div > div.child > img._lazyload
div#slick-slide35 > div > div.child > img._lazyload div#slick-slide35 > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.slick-slide > div > div.child > img._lazyload div.slick-slide > div > div.child > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload
div.part1 > div.list > div.item > img._lazyload div.part1 > div.list > div.item > img._lazyload

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
●Forced reflow
●Optimize viewport for mobile
●Time to Interactive 0.5 s
●Max Potential First Input Delay 30 ms
●Reduce unused JavaScript
●JavaScript execution time 0.3 s
●Avoid non-composited animations 6 animated elements found
●Page didn't prevent back/forward cache restoration
●Network Requests
●Network Round Trip Times 320 ms
●Server Backend Latencies 50 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 550 ms
●Avoid large layout shifts 15 layout shifts found
○INP breakdown
○LCP request discovery
○User Timing marks and measures
○Avoid long main-thread tasks
68

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

Some ARIA parent roles must contain specific child roles to perform their intended accessibility functions. Learn more about roles and required children elements.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
123456 div.body_home > div.banner > div.navg > ul.slick-dots

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.

Internationalization and localization

If a page doesn't specify a `lang` attribute, a screen reader assumes that the page is in the default language that the user chose when setting up the screen reader. If the page isn't actually in the default language, then the screen reader might not announce the page's text correctly. Learn more about the `lang` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
html.home html.home

These are opportunities to improve the interpretation of your content by users in different locales.

Names and labels

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more about the `alt` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

Link text (and alternate text for images, when used as links) that is discernible, unique, and focusable improves the navigation experience for screen reader users. Learn how to make links accessible.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.d2 > div.block > div.logo > a div.d2 > div.block > div.logo > a
div#slick-slide00 > div > div.child > a.a1 div#slick-slide00 > div > div.child > a.a1
div#slick-slide00 > div > div.child > a.a2 div#slick-slide00 > div > div.child > a.a2
div.d2 > div.block > div.logo > a div.d2 > div.block > div.logo > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.block > div.list > div.item > a div.block > div.list > div.item > a
div.text > div.inner > div.l > a div.text > div.inner > div.l > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.inner > div.pic > div.img > a div.inner > div.pic > div.img > a
div.block > div.d2 > div#d1 > a div.block > div.d2 > div#d1 > a
div.block > div.d2 > div#d2 > a div.block > div.d2 > div#d2 > a
div.block > div.d2 > div#d3 > a div.block > div.d2 > div#d3 > a
div.block > div.d4 > div#d4 > a div.block > div.d4 > div#d4 > a
div.block > div.d4 > div#d5 > a div.block > div.d4 > div#d5 > a
div.block > div.d4 > div#d6 > a div.block > div.d4 > div#d6 > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.part1 > div.list > div.item > a div.part1 > div.list > div.item > a
div.footer > div.part2 > div.logo > a div.footer > div.part2 > div.logo > a

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

Best practices

Disabling zooming is problematic for users with low vision who rely on screen magnification to properly see the contents of a web page. Learn more about the viewport meta tag.

Why this matters

Informational: a Permissions-Policy directive showing feature -> allowed origins.

Source: MDN Permissions-Policy

Failing Elements
head > meta head > meta

These items highlight common accessibility best practices.

Navigation

A value greater than 0 implies an explicit navigation ordering. Although technically valid, this often creates frustrating experiences for users who rely on assistive technologies. Learn more about the `tabindex` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
学生|教职工|校友|访客|招聘|捐赠 门户网络邮箱燕云直播图书馆医学部领导信箱 北大概况招生学部与院系教育教学科学研究合作交流校园生活 EN 北大 · 要闻 … body > div.body_b

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
●`[role]` values are valid
●`[aria-*]` attributes have valid values
●`[aria-*]` attributes are valid and not misspelled
●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
●Touch targets have sufficient size and spacing.
●Document has a main landmark.
●Deprecated ARIA roles were not used
●The page contains a heading, skip link, or landmark region
●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
○Buttons have an accessible name
○`<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
○Heading elements appear in a sequentially-descending order
○`<html>` element has a valid value for its `[lang]` attribute
○`<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
○Links are distinguishable without relying on color.
○Lists contain only `<li>` elements and script supporting elements (`<script>` and `<template>`).
○List items (`<li>`) are contained within `<ul>`, `<ol>` or `<menu>` parent elements
○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>`.
○All heading elements contain content.
○Uses ARIA roles only on compatible elements
○Image elements do not have `[alt]` attributes that are redundant text.
○Elements with visible text labels have matching accessible names.
○Tables use `<caption>` instead of cells with the `[colspan]` attribute to indicate a caption.
○`<td>` elements in a large `<table>` have one or more table headers.
96

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.

SourceDescription
www.pku.edu.cn/Public/static/themes/image/bg5.svg
Failed to load resource: the server responded with a status of 404 (Not Found)
www.pku.edu.cn/Public/static/themes/image/bg14.svg
Failed to load resource: the server responded with a status of 404 (Not Found)
●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 clickjacking with XFO or CSP
●Mitigate DOM-based XSS with Trusted Types
●Detected JavaScript libraries
●Page has valid source maps
○Redirects HTTP traffic to HTTPS
82

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
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div#slick-slide01 > div > div.child > a.a1 div#slick-slide01 > div > div.child > a.a1
div#slick-slide05 > div > div.child > a.a1 div#slick-slide05 > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a.a1 div.slick-slide > div > div.child > a.a1
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a
通知公告 div.l > div.title > div.fz40 > a.now
北大声明 div.l > div.title > div.fz40 > a
div#slick-slide30 > div > div.child > a div#slick-slide30 > div > div.child > a
div.slick-slide > div > div.child > a div.slick-slide > div > div.child > a

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

Content Best Practices

Informative elements should aim for short, descriptive alternate text. Decorative elements can be ignored with an empty alt attribute. Learn more about the `alt` attribute.

Why this matters

Performance issues directly impact user engagement and conversion rates.

Failing Elements
div.inner > div.l > a > img div.inner > div.l > a > img

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 have descriptive text
●Document has a valid `hreflang`
○robots.txt is valid
○Document has a valid `rel=canonical`

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