The full list could be found here.
| S | id | title | description |
|---|---|---|---|
| ✅ | uses-responsive-images | Properly size images | Serve images that are appropriately-sized to save cellular data and improve load time. Learn more. |
| ✅ | offscreen-images | Defer offscreen images | Consider lazy-loading offscreen and hidden images after all critical resources have finished loading to lower time to interactive. Learn more. |
| ✅ | unminified-css | Minify CSS | Minifying CSS files can reduce network payload sizes. Learn more. |
| ✅ | unminified-javascript | Minify JavaScript | Minifying JavaScript files can reduce payload sizes and script parse time. Learn more. |
| ✅ | unused-css-rules | Remove unused CSS | Remove dead rules from stylesheets and defer the loading of CSS not used for above-the-fold content to reduce unnecessary bytes consumed by network activity. Learn more. |
| ❌ | uses-optimized-images | Efficiently encode images | Optimized images load faster and consume less cellular data. Learn more. |
| ✅ | uses-webp-images | Serve images in next-gen formats | Image formats like JPEG 2000, JPEG XR, and WebP often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more. |
| ❌ | uses-text-compression | Enable text compression | Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes. Learn more. |
| ✅ | uses-rel-preconnect | Preconnect to required origins | Consider adding preconnect or dns-prefetch resource hints to establish early connections to important third-party origins. Learn more. |
| ❌ | redirects | Avoid multiple page redirects | Redirects introduce additional delays before the page can be loaded. Learn more. |
| ✅ | uses-rel-preload | Preload key requests | Consider using to prioritize fetching resources that are currently requested later in page load. Learn more. |
| ❌ | efficient-animated-content | Use video formats for animated content | Large GIFs are inefficient for delivering animated content. Consider using MPEG4/WebM videos for animations and PNG/WebP for static images instead of GIF to save network bytes. Learn more |