First Input Delay (FID) vs. Interaction to Next Paint (INP)

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This post explains the transition from First Input Delay (FID) to Interaction to Next Paint (INP) as a Core Web Vital. It details the components of INP (Input Delay, Processing Delay, Presentational Delay) and contrasts it with FID's limitations. Optimization strategies for INP are provided, focusing on reducing processing delay (profiling, debouncing/throttling, code splitting, breaking down long tasks) and presentational delay (using `will-change`, `transform`/`opacity`, `content-visibility`, reducing forced synchronous layouts, using web workers). Event handling optimizations include deferring non-critical events, using passive event listeners, and event delegation. Measurement tools like Vercel Speed Insights, PageSpeed Insights, and Lighthouse are mentioned.