LCP (Largest Contentful Paint)
LCP measures the time from page load to the rendering of the largest visible element — a banner image or heading block. Google’s threshold for a good experience is LCP under 2.5 seconds on real user connections.
In practice
Common culprits: heavy unresized images, render-blocking fonts, scripts that delay the first meaningful paint. Proven fixes: AVIF or WebP formats, preloading the main hero resource, server-side rendering. One subtlety: a minor banner can be the 'largest element' — confirming what element triggers LCP before optimizing prevents wasted effort.