Largest Contentful Paint (LCP)

LCP measures the moment the biggest element in the viewport - usually a hero image, heading, or block of text - has rendered. It's a good proxy for "how quickly does this page feel loaded?". Google considers 2.5 seconds or less to be good.

Common causes of poor LCP are large unoptimised images, slow server responses, and render-blocking scripts and styles. Fixing them is often the single biggest speed win available.