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

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

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

This is the largest contentful element painted within the viewport

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

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

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

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

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

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

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

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

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

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

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

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 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/).

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)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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/).