LCP (Largest Contentful Paint) is a Core Web Vitals metric measuring the time from page navigation until the largest visible content element renders on screen.
The "largest contentful element" is determined automatically by the browser; on most ecommerce pages it is the hero image on the home, PLP, or PDP, or the H1 on a blog/article page. 2026 thresholds: ≤ 2.5s good, ≤ 4.0s needs improvement, > 4.0s poor.
Common LCP fixes for ecommerce: preload the LCP image with <link rel="preload" as="image" fetchpriority="high">, serve modern formats (AVIF/WebP), use priority on Next.js Image components, render the page server-side (or stream from edge), inline critical CSS, and avoid lazy-loading the LCP image.
LCP is heavily influenced by network conditions and CDN performance. Edge rendering (TTFB ≤ 100ms) sets a structural floor that monolithic origin-rendered sites cannot match.