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 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

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

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

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

This is the largest contentful element painted within the viewport

Some third-party embeds can be lazy loaded. Consider replacing them with a facade until they are required

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

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

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

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

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)

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading

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

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

Consider instrumenting your app with the User Timing API to measure your app's real-world performance during key user experiences

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

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity

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

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

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

Reduce unused JavaScript and defer loading scripts until they are required to decrease 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

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

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

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

Reduce unused rules from stylesheets and defer CSS not used for above-the-fold content to decrease bytes consumed by network activity

Some third-party embeds can be lazy loaded. Consider replacing them with a facade until they are required

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

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

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

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

Consider instrumenting your app with the User Timing API to measure your app's real-world performance during key user experiences

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

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

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

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 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

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

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)

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

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

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

Third-party code can significantly impact load performance. Limit the number of redundant third-party providers and try to load third-party code after your page has primarily finished loading