Long Animation Frames (LoAF)
The Long Animation Frames (LoAF) API is a modern browser API designed to diagnose responsiveness issues. It provides detailed attribution for slow UI updates (known as "long frames"), helping developers understand the root cause of jank and poor interactivity. It is an advanced diagnostic tool for pinpointing the exact scripts or rendering work that contribute to a bad Interaction to Next Paint (INP) score.
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.