Definition LCP represents the perceived load speed of the page. As the page renders, the browser tracks the largest element and updates the final LCP value until user interaction occurs.
How it works The browser monitors img, video poster, background-image, and text blocks within the viewport. The largest element is reevaluated at each render step. User interaction (click, scroll, keypress) stops LCP measurement. The result is that last value. CDN, server response time, render blockers, and image size directly affect LCP.
Where you see it in Scope Trends The **Core Web Vitals** report shows LCP at the 75th percentile per page. **Site Crawl** lists each page's LCP candidate element and the cause.
Frequently asked questions **What are the LCP thresholds?** Good <= 2.5s, needs improvement 2.5-4s, poor > 4s. Mobile uses the same threshold.
**Fastest way to improve LCP?** Reduce server response time, preload the LCP image, defer render-blocking JS, inline critical CSS.