Largest Contentful Paint (LCP)
A Core Web Vital that measures the perceived loading speed of a page. It marks the point in time when the largest content element (usually a hero image or a large block of text) becomes visible within the viewport. LCP is a critical metric because it signals to the user that the main content of the page has arrived, answering their question, "Is it useful?". It is a primary focus for both user experience optimization and SEO.
Related web performance terms
- Lab Data (Synthetic Monitoring)
Lab data is performance data collected in a controlled, repeatable environment using tools like Google Lighthouse or WebPageTest.
- Largest Contentful Paint Subparts
The LCP Subparts are the distinct phases that make up the total Largest Contentful Paint time. Analyzing this breakdown is crucial for diagnosing the root cause of a slow LCP.
- Layout Thrashing
Layout Thrashing is a harmful performance anti-pattern.
- Lazy loading
Lazy loading is an optimization strategy where content that is not immediately visible to the user—typically images and videos "below the fold"—is deferred and only loaded as the user scrolls down…