Lighthouse Desktop
· 0 checks — Desktop Lighthouse audit -- Performance, Accessibility, Best Practices, and SEO category breakdown.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.
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
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.
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.
Performance issues directly impact user engagement and conversion rates.
Each subpart has specific improvement strategies. Ideally, most of the LCP time should be spent on loading the resources, not within delays.
Performance issues directly impact user engagement and conversion rates.
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.
Performance issues directly impact user engagement and conversion rates.
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.
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.
Performance issues directly impact user engagement and conversion rates.
| Request | Cache TTL | Transfer Size |
|---|---|---|
| www.gstatic.com/eureka/clank/146/cast_sender.js | 86400.0 s | 13.1 KiB |
| static.doubleclick.net/instream/ad_status.js | 900.0 s | 495 B |
These insights are also available in the Chrome DevTools Performance Panel - record a trace to view more detailed information.
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.
Performance issues directly impact user engagement and conversion rates.
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.
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.
Performance issues directly impact user engagement and conversion rates.
| URL | Transfer Size | Est Savings |
|---|---|---|
| /s/_/ytmainappweb/_/ss/k=ytmainappweb.kevlar_base.KgArE42... | 269.3 KiB | 261.3 KiB |
| www.youtube.com/s/player/8fb635c2/www-player.css | 57.9 KiB | 57.9 KiB |
| /css2?family=Roboto:wght@300;400;500;700&family=YouTube+S... | 14.9 KiB | 14.9 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.
Performance issues directly impact user engagement and conversion rates.
| URL | Transfer Size | Est Savings |
|---|---|---|
| /s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.H... | 1.8 MiB | 1.1 MiB |
| www.youtube.com/s/player/8fb635c2/player_es6.vflset/en_US/base.js | 640.8 KiB | 476.8 KiB |
| www.youtube.com/s/player/8fb635c2/player_es6.vflset/en_US/remote.js | 34.3 KiB | 26.8 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.
Performance issues directly impact user engagement and conversion rates.
| URL | Total CPU Time | Script Evaluation | Script Parse |
|---|---|---|---|
| /s/_/ytmainappweb/_/js/k=ytmainappweb.kevlar_base.en_US.H... | 2.2 s | 1.6 s | 308 ms |
| Unattributable | 623 ms | 141 ms | 0.0 ms |
| /s/desktop/14cba078/jsbin/web-animations-next-lite.min.vf... | 502 ms | 398 ms | 1.8 ms |
| www.youtube.com/ | 257 ms | 27 ms | 31 ms |
| www.youtube.com/s/player/8fb635c2/player_es6.vflset/en_US/base.js | 165 ms | 76 ms | 82 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
Performance issues directly impact user engagement and conversion rates.
| Category | Time Spent |
|---|---|
| Script Evaluation | 3.1 s |
| Other | 513 ms |
| Script Parsing & Compilation | 441 ms |
| Style & Layout | 222 ms |
| Parse HTML & CSS | 201 ms |
| Garbage Collection | 124 ms |
| Rendering | 16 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
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.
Performance issues directly impact user engagement and conversion rates.
More information about the performance of your application. These numbers don't directly affect the Performance score.
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.
Best practices
Touch targets with sufficient size and spacing help users who may have difficulty targeting small controls to activate the targets. Learn more about touch targets.
Performance issues directly impact user engagement and conversion rates.
| Failing Elements |
|---|
About ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Press ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Copyright ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Contact us ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Creators ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Developers ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-primary > a |
Terms ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a |
Privacy ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a |
How YouTube works ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a |
Test new features ytd-guide-renderer#guide-renderer > div#footer > div#guide-links-secondary > a |
These items highlight common accessibility best practices.
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
Performance issues directly impact user engagement and conversion rates.
| Source | Description |
|---|---|
Failed to load resource: the server responded with a status of 403 () | |
Failed to load resource: the server responded with a status of 403 () | |
Failed to load resource: the server responded with a status of 403 () | |
Failed to load resource: the server responded with a status of 403 () | |
Failed to load resource: the server responded with a status of 403 () | |
Failed to load resource: the server responded with a status of 403 () |
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.
Performance issues directly impact user engagement and conversion rates.
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
Performance issues directly impact user engagement and conversion rates.
| Uncrawlable Link |
|---|
div.ytp-title-expanded-overlay > div.ytp-title-expanded-heading > div.ytp-title-expanded-title > a div.ytp-title-expanded-overlay > div.ytp-title-expanded-heading > div.ytp-title-expanded-title > a |
div.ytp-chrome-top > div.ytp-title > div.ytp-title-text > a.ytp-title-link div.ytp-chrome-top > div.ytp-title > div.ytp-title-text > a.ytp-title-link |
div.ytp-overlays-container > div.ytp-overlay-top-left > div.ytp-paid-content-overlay > a.ytp-paid-content-overlay-link div.ytp-overlays-container > div.ytp-overlay-top-left > div.ytp-paid-content-overlay > a.ytp-paid-content-overlay-link |
div#ytp-id-6 > div.ytp-playlist-menu-header > div.ytp-playlist-menu-title > a.ytp-playlist-menu-title-name div#ytp-id-6 > div.ytp-playlist-menu-header > div.ytp-playlist-menu-title > a.ytp-playlist-menu-title-name |
div#movie_player > div#ytp-id-9 > div.ytp-share-panel-inner-content > a.ytp-share-panel-link div#movie_player > div#ytp-id-9 > div.ytp-share-panel-inner-content > a.ytp-share-panel-link |
To appear in search results, crawlers need access to your app.