Lighthouse
Lighthouse is an open-source, automated tool from Google for auditing the quality of web pages. It runs a series of tests against a page and generates a report with scores for performance, accessibility, SEO, and other best practices. Its performance score is based on Lab Data and is an excellent tool for debugging and regression testing, but it should not be confused with the Field Data from CrUX that Google uses for its search ranking.
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 (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.
- 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.