INP replaced First Input Delay (FID) in March 2024. Unlike FID, which only measured the first interaction, INP considers every click, tap, and keyboard input during the session and reports the worst.
How to improve it
- Break long JavaScript tasks into smaller chunks with yielding.
- Debounce event handlers on high-frequency inputs.
- Reduce main-thread work during interaction — defer analytics, hydration, and non-critical rendering.
- Avoid layout thrashing inside event handlers.
Example
A dashboard with 350 ms INP improves to 140 ms after splitting a monolithic table-render function into a React Suspense boundary with streaming SSR.
How SEM Optimiser reports it
INP is reported at the URL level with the worst-performing interaction highlighted so engineers can profile it directly.
Related terms
- Core Web Vitals
Core Web Vitals is a set of three page-experience metrics Google uses to measure loading performance, interactivity, and visual stability: LCP, INP, and CLS.
- LCP (Largest Contentful Paint)
Largest Contentful Paint is the time from navigation start until the largest visible element in the viewport has been rendered, and should be under 2.5 seconds.
- CLS (Cumulative Layout Shift)
Cumulative Layout Shift measures how much the visible layout of a page moves unexpectedly during load, and should be under 0.1.