These checks ensure that your page is optimized for users to be able to see and interact with page content.
- Performance audit scoring #
- Lighthouse performance scoring Learn how Lighthouse generates the overall Performance score for your page.
- Lighthouse performance scoring
- Metrics #
- First Contentful Paint Learn about Lighthouse's First Contentful Paint metric and how to measure and optimize it.
- Speed Index Learn about Lighthouse's Speed Index metric and how to optimize it.
- Total Blocking Time Learn about Lighthouse's Total Blocking Time metric and how to measure and optimize it.
- Largest Contentful Paint Learn about Lighthouse's Largest Contentful Paint metric and how to measure and optimize it.
- Cumulative Layout Shift Learn about the Cumulative Layout Shift (CLS) metric and how to optimize for it.
- First Contentful Paint
- Opportunities #
- Eliminate render-blocking resources Learn about the render-blocking-resources audit.
- Properly size images Learn about the uses-responsive-images audit.
- Defer offscreen images Learn about the offscreen-images audit.
- Minify CSS Learn about the unminified-css audit.
- Remove unused CSS Learn about the unused-css-rules audit.
- Efficiently encode images Learn about the uses-optimized-images audit.
- Serve images in modern formats Learn about the uses-webp-images audit.
- Enable text compression Learn about how enabling text compression can improve your webpage load performance.
- Preconnect to required origins Learn about the uses-rel-preconnect audit.
- Reduce server response times (TTFB) Learn about the time-to-first-byte audit.
- Avoid multiple page redirects Learn why page redirects slow down your web page's load speed and how to avoid them.
- Preload key requests Learn about the uses-rel-preload audit.
- Use video formats for animated content Learn about the efficient-animated-content audit.
- Reduce the impact of third-party code Learn how third-party code, like advertising networks and analytics services, affects page load performance, and how you can optimize third-party code.
- Avoid non-composited animations How to pass the "Avoid non-composited animations" Lighthouse audit.
- Lazy load third-party resources with facades Learn about the opportunities to lazy load third-party resources with facades.
- Eliminate render-blocking resources
- Diagnostics #
- Avoid enormous network payloads Learn how to improve your web page's load time by reducing the total file size of resources you serve to your users.
- Serve static assets with an efficient cache policy Learn how caching your web page's static resources can improve performance and reliability for repeat visitors.
- Avoid an excessive DOM size Learn how a large DOM can reduce your web page's performance and how you can reduce the size of your DOM at load time.
- Avoid chaining critical requests Learn what critical request chains are, how they affect web page performance, and how you can reduce the effect.
- User Timing marks and measures Learn how the User Timing API can help you get real-world performance data for your web page.
- Minimize main thread work Learn about the browser's main thread and how you can optimize your web page to reduce main thread load and improve performance.
- Ensure text remains visible during webfont load Learn how to use the font-display API to make sure your web page text will always be visible to your users.
- Keep request counts low and transfer sizes small Learn how high resource counts and large transfer sizes affect load performance. Get strategies for reducing request counts and transfer sizes.
- Ensure the page can be restored from the back/forward cache How to use Lighthouse to test if a page can be restored from the back/forward cache.
- Avoid enormous network payloads
- Retired metrics #
- Time to Interactive Learn about Lighthouse's Time to Interactive metric and how to measure and optimize it.
- First Meaningful Paint Learn about Lighthouse's deprecated First Meaningful Paint metric and how to measure and optimize it.
- First CPU Idle Learn about Lighthouse's deprecated First CPU Idle metric and how to optimize it.
- Max Potential First Input Delay Learn about Lighthouse's deprecated Max Potential First Input Delay metric and how to measure and optimize it.
- Time to Interactive