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

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

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

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

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

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

Redirects introduce additional delays before the page can be loaded

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

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

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

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

This is the largest contentful element painted within the viewport

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

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

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

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

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

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)

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

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

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

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

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

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

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

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

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

This is the largest contentful element painted within the viewport

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

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

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

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

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)

Redirects introduce additional delays before the page can be loaded

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

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

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

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

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

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

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

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