Why it matters to a buyer
A slow response to a tap or click, an add-to-cart button that takes a full second to react, is exactly the kind of friction that quietly loses conversions before a visitor ever reaches checkout. INP matters to a buyer because it is judged across every interaction on a visit, not just the first one, so a page that feels sluggish partway through browsing will score poorly even if it loaded and responded fine at first.
How it is measured or applied
Poor INP is usually caused by heavy JavaScript that blocks the browser's main thread, large event handler code, or third-party scripts, like chat widgets and ad tags, competing for the same thread as the visitor's interaction. Fixing it means breaking up long JavaScript tasks, deferring non-critical scripts, and reducing what runs in response to an interaction. Real-world INP is reported in the Chrome User Experience Report, visible in PageSpeed Insights and Search Console's Core Web Vitals report, and specific slow interactions are diagnosed in Chrome DevTools' Performance panel.
Sources
- Interaction to Next Paint (INP), web.dev (Google)
