- Agentic Browsing
- A Lighthouse category (13.3+, beta) that checks how usable a page is for AI agents. Shown as checks passed, not as a 0 to 100 score.
- Chrome UX Report CrUX
- CrUX is a public dataset of real-user performance from Chrome, reported at the 75th percentile over a rolling 28-day window.
- Core Web Vitals
- Core Web Vitals are three user-experience metrics, LCP, INP and CLS, assessed on real-user data at the 75th percentile.
- Cumulative Layout Shift CLS
- CLS measures how much visible content moves around unexpectedly while a page loads and is used. A good CLS is 0.1 or less.
- First Contentful Paint FCP
- FCP measures when the browser first renders any text, image or non-white canvas from the page. A good FCP is 1.8 seconds or less.
- Interaction to Next Paint INP
- INP measures how quickly a page responds visually to clicks, taps and key presses across a visit. A good INP is 200 milliseconds or less.
- Largest Contentful Paint LCP
- LCP measures how long it takes for the largest image or text block in the viewport to render. A good LCP is 2.5 seconds or less.
- Lighthouse score
- A 0 to 100 rating for Performance, Accessibility, Best Practices and SEO. Performance is a weighted average of five lab metrics; 90+ is good.
- Speed Index SI
- Speed Index is a Lighthouse lab metric that shows how quickly the visible content of a page fills in during load. Lower is better.
- Time to First Byte TTFB
- TTFB measures the time from the request until the first byte of the response arrives. A good TTFB is 0.8 seconds or less.
- Total Blocking Time TBT
- TBT is a Lighthouse lab metric that adds up how long the main thread was blocked by long tasks after First Contentful Paint.