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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 about efficient video formats

Reduce unused JavaScript and defer loading scripts until they are required to decrease bytes consumed by network activity. Learn how to reduce unused JavaScript.

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

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.

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles. Learn how to eliminate render-blocking resources.

If the LCP element is dynamically added to the page, you should preload the image in order to improve LCP. Learn more about preloading LCP elements.

This is the largest contentful element painted within the viewport. Learn more about the Largest Contentful Paint element

Serve images that are appropriately-sized to save cellular data and improve load time. Learn how to size images.

A long cache lifetime can speed up repeat visits to your page. Learn more about efficient cache policies.

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

Consider marking your touch and wheel event listeners as `passive` to improve your page's scroll performance. Learn more about adopting passive event listeners.

For users on slow connections, external scripts dynamically injected via `document.write()` can delay page load by tens of seconds. Learn how to avoid document.write().

Consider lazy-loading offscreen and hidden images after all critical resources have finished loading to lower time to interactive. Learn how to defer offscreen images.

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

Leverage the `font-display` CSS feature to ensure text is user-visible while webfonts are loading. Learn more about `font-display`.

Set an explicit width and height on image elements to reduce layout shifts and improve CLS. Learn how to set image dimensions

Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption. Learn more about modern image formats.

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.

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.

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.

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

Deprecated APIs will eventually be removed from the browser. Learn more about deprecated APIs.

Image display dimensions should match natural aspect ratio. Learn more about image aspect ratio.

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding mixed content, where some resources are loaded over HTTP despite the initial request being served over HTTPS. HTTPS prevents intruders from tampering with or passively listening in on the communications between your app and your users, and is a prerequisite for HTTP/2 and many new web platform APIs. Learn more about HTTPS.

Make sure that you redirect all HTTP traffic to HTTPS in order to enable secure web features for all your users. Learn more.

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.

Screen reader users rely on frame titles to describe the contents of frames. Learn more about frame titles.

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.

Low-contrast text is difficult or impossible for many users to read. Learn how to provide sufficient color contrast.

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.