LCP (Largest Contentful Paint)

A good LCP value is 2.5 seconds or less, assessed at the 75th percentile of real page views. Contrary to a widespread misconception, the file size of the image is rarely the bottleneck: according to Google, most websites with poor LCP spend less than ten per cent of that time downloading the LCP image. The bulk goes on server response time (TTFB) and on the delay before the browser requests the image at all. What works, in this order, is a fast server response with caching, requesting the LCP image early and at high priority (no `loading="lazy"`, use `fetchpriority="high"` or `preload` instead), removing render-blocking resources – and only then image compression. That images are the LCP element on 76 per cent of mobile and 85 per cent of desktop pages tells you which element is measured, not where the time goes. Because LCP is closely tied to perceived load time, it is the Core Web Vital that users feel most directly.