Interaction to Next Paint (INP)

Interaction to Next Paint measures responsiveness across the whole visit, not just the first interaction the way the older First Input Delay metric did. It looks at the delay between a user action and the next frame the browser paints in response, then reports a value representative of the page’s worst interactions.

A good INP is 200 milliseconds or faster. Poor scores almost always trace back to heavy JavaScript: large bundles, long tasks that block the main thread, and event handlers that try to do too much at once.

Improving INP means shipping less JavaScript, breaking long tasks into smaller pieces, deferring non-critical scripts until the browser is idle, and keeping third-party tags lean. Static-first frameworks have a structural advantage here, because most of the page is already HTML and CSS rather than client-side script.