If your robots.txt file is malformed, crawlers may not be able to understand how you want your website to be crawled or indexed

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

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

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

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

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

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

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

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

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

Image formats like WebP and AVIF 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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

If your robots.txt file is malformed, crawlers may not be able to understand how you want your website to be crawled or indexed

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

This is the largest contentful element painted within the viewport

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