By Zach Wennstedt, founder of Eye To Ad Media · 2026-09-29
Interaction to Next Paint (INP) is a Core Web Vitals metric that measures how quickly a page visibly responds after a user clicks, taps or types. Google considers an INP of 200 milliseconds or less good, 200 to 500 milliseconds in need of improvement, and over 500 milliseconds poor. Slow INP is usually caused by long JavaScript tasks on the main thread.
You tap "Add to cart." Nothing happens. You tap again. Now it is in your cart twice. That hesitation is what INP measures, and your visitors feel it long before they could name it.
INP replaced First Input Delay as a Core Web Vital in March 2024. The difference matters: First Input Delay only measured the first interaction and only the delay before the browser started handling it. INP looks at interactions throughout the visit and measures all the way until the screen actually updates. Google's thresholds are documented at web.dev.
What makes INP slow
- Long tasks: big chunks of JavaScript that block the main thread, so the browser cannot respond.
- Third-party scripts: chat widgets, trackers and ad tags that run code on every interaction.
- Heavy event handlers: a click that triggers expensive work before the page can repaint.
- Huge DOMs: pages with thousands of elements take longer to update after every change.
- Page builders and plugin stacks: common on WordPress and Shopify sites. See WordPress SEO and Shopify SEO.
How to fix it
- Measure real users first. PageSpeed Insights and the Search Console Core Web Vitals report show field data. Lab tests alone can miss INP.
- Find the long tasks. The Performance panel in Chrome DevTools shows exactly which script blocks an interaction.
- Break up the work. Yield to the main thread between chunks so the browser can paint.
- Update the screen first, work second. Show the response immediately, then do the heavy lifting.
- Cut or defer third parties. Load non-essential widgets after interaction or remove them.
- Shrink the DOM. Fewer elements, simpler layouts, less work per update.
INP work is engineering work: it lives in your code, not in a settings panel. It is a core part of our page speed optimization service.