Performance
Interaction to Next Paint (INP)
A Core Web Vital measuring how quickly a page visibly responds to clicks, taps and key presses across a visit; it replaced First Input Delay in March 2024.
INP times each interaction from the moment of input until the browser paints the next frame. That includes any wait for the browser to become free, the time the page’s event handlers take to run, and the time to draw the result. The reported value is close to the slowest interaction of the visit, so one sluggish menu can fail an otherwise fast page. Its predecessor, First Input Delay, measured only the wait before the first interaction was handled.
A good INP is 200 milliseconds or less at the 75th percentile of visits (web.dev). Poor scores usually come from JavaScript: large bundles, long tasks that block the browser’s main thread, heavy third-party tags, and event handlers that do a lot of work before updating the screen.
The fixes are to ship less JavaScript, break long tasks into smaller pieces, update the screen first and finish other work afterward, and remove tags nobody uses. Pages built mostly from HTML and CSS start with an advantage. Our INP optimization guide covers diagnosis in more detail.
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