A long cache lifetime can speed up repeat visits to your page

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

Time to interactive is the amount of time it takes for the page to become fully interactive

This is the largest contentful element painted within the viewport

Optimized images load faster and consume less cellular data

Minifying CSS files can reduce network payload sizes

Estimated Input Latency is an estimate of how long your app takes to respond to user input, in milliseconds, during the busiest 5s window of page load. If your latency is higher than 50 ms, users may perceive your app as laggy

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles

Cumulative Layout Shift measures the movement of visible elements within the viewport

Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes

Some third-party scripts may contain known security vulnerabilities that are easily identified and exploited by attackers

These DOM elements contribute most to the CLS of the page.

Network round trip times (RTT) have a large impact on performance. If the RTT to an origin is high, it's an indication that servers closer to the user could improve performance

The maximum potential First Input Delay that your users could experience is the duration of the longest task

First CPU Idle marks the first time at which the page's main thread is quiet enough to handle input. [Learn more](https://web.dev/first-cpu-idle/).

Large JavaScript libraries can lead to poor performance. Prefer smaller, functionally equivalent libraries to reduce your bundle size

The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load

To set budgets for the quantity and size of page resources, add a budget.json file

Minifying JavaScript files can reduce payload sizes and script parse time

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this

Largest Contentful Paint marks the time at which the largest text or image is painted

First Meaningful Paint measures when the primary content of a page is visible

Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds

Server latencies can impact web performance. If the server latency of an origin is high, it's an indication the server is overloaded or has poor backend performance

Large network payloads cost users real money and are highly correlated with long load times

Remove unused JavaScript to reduce bytes consumed by network activity

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this

Speed Index shows how quickly the contents of a page are visibly populated

First Contentful Paint marks the time at which the first text or image is painted

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding [mixed content](https://developers.google.com/web/fundamentals/security/prevent-mixed-content/what-is-mixed-content), where some resources are loaded over HTTP despite the initial request being servedover 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

Keep the server response time for the main document short because all other requests depend on it

A large DOM will increase memory usage, cause longer [style calculations](https://developers.google.com/web/fundamentals/performance/rendering/reduce-the-scope-and-complexity-of-style-calculations), and produce costly [layout reflows](https://developers.google.com/speed/articles/reflow)

The maximum potential First Input Delay that your users could experience is the duration of the longest task

Consider reducing the time spent parsing, compiling and executing JS. You may find delivering smaller JS payloads helps with this

Text-based resources should be served with compression (gzip, deflate or brotli) to minimize total network bytes

A large DOM will increase memory usage, cause longer [style calculations](https://developers.google.com/web/fundamentals/performance/rendering/reduce-the-scope-and-complexity-of-style-calculations), and produce costly [layout reflows](https://developers.google.com/speed/articles/reflow)

All sites should be protected with HTTPS, even ones that don't handle sensitive data. This includes avoiding [mixed content](https://developers.google.com/web/fundamentals/security/prevent-mixed-content/what-is-mixed-content), where some resources are loaded over HTTP despite the initial request being servedover 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

Resources are blocking the first paint of your page. Consider delivering critical JS/CSS inline and deferring all non-critical JS/styles

Large network payloads cost users real money and are highly correlated with long load times

The Critical Request Chains below show you what resources are loaded with a high priority. Consider reducing the length of chains, reducing the download size of resources, or deferring the download of unnecessary resources to improve page load

Speed Index shows how quickly the contents of a page are visibly populated

Large JavaScript libraries can lead to poor performance. Prefer smaller, functionally equivalent libraries to reduce your bundle size

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

Network round trip times (RTT) have a large impact on performance. If the RTT to an origin is high, it's an indication that servers closer to the user could improve performance

Server latencies can impact web performance. If the server latency of an origin is high, it's an indication the server is overloaded or has poor backend performance

First Meaningful Paint measures when the primary content of a page is visible

First Contentful Paint marks the time at which the first text or image is painted

Sum of all time periods between FCP and Time to Interactive, when task length exceeded 50ms, expressed in milliseconds

Largest Contentful Paint marks the time at which the largest text or image is painted

This is the largest contentful element painted within the viewport

Minifying JavaScript files can reduce payload sizes and script parse time

First CPU Idle marks the first time at which the page's main thread is quiet enough to handle input. [Learn more](https://web.dev/first-cpu-idle/).

Consider reducing the time spent parsing, compiling, and executing JS. You may find delivering smaller JS payloads helps with this

Minifying CSS files can reduce network payload sizes

First Contentful Paint 3G marks the time at which the first text or image is painted while on a 3G network

Cumulative Layout Shift measures the movement of visible elements within the viewport

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

Time to interactive is the amount of time it takes for the page to become fully interactive

A long cache lifetime can speed up repeat visits to your page

Optimized images load faster and consume less cellular data

To set budgets for the quantity and size of page resources, add a budget.json file

Some third-party scripts may contain known security vulnerabilities that are easily identified and exploited by attackers

Lists the longest tasks on the main thread, useful for identifying worst contributors to input delay

These DOM elements contribute most to the CLS of the page.

Estimated Input Latency is an estimate of how long your app takes to respond to user input, in milliseconds, during the busiest 5s window of page load. If your latency is higher than 50 ms, users may perceive your app as laggy

Keep the server response time for the main document short because all other requests depend on it

Remove unused JavaScript to reduce bytes consumed by network activity