Largest Contentful Paint

Definitions

1. A Core Web Vital metric measuring when the largest content element (hero image, heading, video poster) becomes visible in the viewport. Best proxy for perceived page load speed. Good: < 2.5s, Poor: > 4s. Improved by optimizing the critical rendering path, preloading hero images, using responsive images, and reducing server response time.

   In plain English: How long it takes for the main content of a page to become visible — the most important speed metric for user experience.

   Example: "LCP is 4.1s because the hero image is a 2MB unoptimized PNG loaded lazily — convert to WebP, set fetchpriority=high, and preload it."

Related Terms

• Allocator
• Big-O
• Cache
• Core Web Vitals
• Cumulative Layout Shift
• First Contentful Paint
• Token Per Second
• Lighthouse Score Obsession