What is TBT (Total Blocking Time)?
TBT measures the total time a page is blocked and unresponsive to user interactions.
Targets
- ●Good: < 200ms
- ●Needs improvement: 200-600ms
- ●Poor: > 600ms
SEO Impact
TBT correlates with INP (Core Web Vital). High TBT = slow page responsiveness.
Related Terms
What are Core Web Vitals?
Core Web Vitals are 3 Google metrics measuring the speed, responsiveness, and visual stability of a web page.
What is CLS (Cumulative Layout Shift)?
CLS measures a page's visual stability. A poor CLS means elements move around during loading.
What is LCP (Largest Contentful Paint)?
LCP measures the loading time of the largest visible element on a page. Target: under 2.5 seconds.
What is Page Loading Speed?
Loading speed measures the time needed to fully display a web page. It's a Google ranking factor.
What is Lazy Loading?
Lazy loading is a technique that delays loading images and videos until they're visible on screen.
What is Google Lighthouse?
Lighthouse is a Google tool that audits a web page's performance, accessibility, SEO, and best practices.