Largest Contentful Paint.

Largest Contentful Paint (LCP) measures the time from when a page starts loading to when the largest content element visible in the viewport is fully rendered. This element is typically a hero image, video poster, or large text block. LCP is considered a strong proxy for perceived loading speed because it measures when the main content becomes visible to the user.

LCP Thresholds

Google's thresholds: Good = under 2.5 seconds; Needs Improvement = 2.5–4 seconds; Poor = over 4 seconds. LCP is measured at the 75th percentile of all page views to capture the experience of most users, including those on slower connections or devices.

Common LCP Improvements

The most impactful LCP improvements include: preloading the LCP image using `<link rel='preload'>`; serving images in modern formats (WebP, AVIF); using a CDN to reduce server response time; removing render-blocking resources; and optimising server-side caching. For image-heavy pages, ensuring the LCP image is in the HTML source (not dynamically injected by JavaScript) is critical, as lazy loading the LCP element significantly worsens scores.