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

Service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. With proper service worker and manifest implementations, browsers can proactively prompt users to add your app to their homescreen, which can lead to higher engagement

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

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

These DOM elements contribute most to the CLS of the page

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

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

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

Serve images that are appropriately-sized to save cellular data and improve load time

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

This is the largest contentful element painted within the viewport

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

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

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

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

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

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

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

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

Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption

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)

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

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

Image formats like WebP and AVIF often provide better compression than PNG or JPEG, which means faster downloads and less data consumption

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

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

This is the largest contentful element painted within the viewport

These DOM elements contribute most to the CLS of the page

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

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

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

Font sizes less than 12px are too small to be legible and require mobile visitors to “pinch to zoom” in order to read. Strive to have >60% of page text ≥12px

Serve images that are appropriately-sized to save cellular data and improve load time

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

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

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

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

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

Interactive elements like buttons and links should be large enough (48x48px), or have enough space around them, to be easy enough to tap without overlapping onto other elements

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

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

Service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications. With proper service worker and manifest implementations, browsers can proactively prompt users to add your app to their homescreen, which can lead to higher engagement

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)