LCP (Largest Contentful Paint)

Definition

Largest Contentful Paint (LCP) measures perceived loading speed by marking the point in the page load timeline when the main content has likely loaded. Specifically, it records the render time of the largest image, video, or text block visible within the viewport. A good LCP score is 2.5 seconds or less. Common causes of poor LCP include slow server response times, render-blocking JavaScript and CSS, slow resource load times, and client-side rendering. Optimizations include using a CDN, preloading critical resources, optimizing images (WebP/AVIF), and implementing efficient CSS delivery.