Performance
INP
Interaction to Next Paint
Interaction to Next Paint (INP) measures the longest single-interaction latency a user experiences on a page, from input to the next visual update. It replaced FID as a Core Web Vital in March 2024.
In depth
INP captures the worst case rather than the average — Google reports the highest interaction delay (with a small allowance for outliers on long sessions) because users remember the worst delay, not the average. Good is under 200 ms, poor is over 500 ms.
High INP is almost always caused by long tasks on the main thread — heavy JavaScript that blocks event handlers from running. Fixes include code-splitting, deferring non-critical scripts, using `requestIdleCallback`, and breaking up long tasks with `await scheduler.yield()`.
Why it matters
INP is the new responsiveness benchmark. Sites built with large React/Vue bundles and many third-party scripts often fail INP even when LCP and CLS are green. It is the hardest Core Web Vital to fix because it requires touching application code, not just static assets.
How Lemwatch helps with inp
Lemwatch monitors inp continuously and alerts you the moment something changes.
Performance monitoring →Related terms
Core Web Vitals
Core Web Vitals are a set of three Google-defined metrics that measure real-user experience on a webpage: Larg…
LCP
Largest Contentful Paint (LCP) measures the time from navigation start until the largest visible element on th…
CLS
Cumulative Layout Shift (CLS) measures how much visible content unexpectedly moves around the page during load…
Page Speed
Page speed is a colloquial term covering the time a page takes to become visually complete and interactive. It…
CDN
A Content Delivery Network (CDN) is a globally distributed set of caching servers that serve static assets and…
Browse the full Lemwatch monitoring glossary (47 terms).