Interaction to Next Paint (INP)

Definition

Interaction to Next Paint (INP) is Google\'s responsiveness Core Web Vital, which replaced First Input Delay (FID) on 12 March 2024. INP measures the time from when a user interacts with a page (click, tap, or keyboard press) to when the browser paints the next frame — the visual response to that interaction. Unlike FID (which measured only the delay of the first interaction), INP measures the worst interaction latency across all interactions during a page visit, reporting the 98th percentile (one interaction in 50 is allowed to be slow without affecting the INP score). **Thresholds (p75 from CrUX):** Good: ≤200ms; Needs Improvement: 200ms–500ms; Poor: >500ms. INP is high when: (1) JavaScript long tasks are running on the main thread — long tasks (>50ms) block the browser from processing input events promptly. Each long task adds to input latency. (2) Event handler callbacks do expensive work synchronously (DOM manipulation, forced layout reflow, heavy computation) before yielding to the browser. (3) Render updates triggered by interactions are complex — large DOM trees, CSS that requires expensive recalculation. Fix: break up long tasks using `setTimeout(callback, 0)` or `scheduler.yield()` to yield to the browser between work items; move expensive work off the main thread using Web Workers; defer non-critical JavaScript; remove unused third-party scripts that create long tasks.

Why it matters for SEO

INP became a Page Experience ranking signal when it replaced FID on 12 March 2024. Pages with Poor INP may be ranked below equivalent pages with Good INP in competitive SERPs. From a UX perspective, high INP means UI elements appear unresponsive to user input — buttons that don\'t react immediately, menus that lag, form fields that delay character rendering — which increases bounce and reduces conversion rates. The most common source of poor INP in modern web applications is third-party scripts (analytics, chat widgets, A/B testing tools, advertising tags) that run on the main thread and block event processing.

How DeepSEOAnalysis checks this

DeepSEOAnalysis surfaces INP from CrUX field data (p75, 28-day window) at URL level — the same data used by Google Search Console\'s Core Web Vitals report and the Page Experience ranking signal. The audit flags pages with Poor INP (>500ms) and Needs Improvement INP (200–500ms) for prioritised attention. The technical root cause of INP (which specific long task or event handler) requires profiling in Chrome DevTools Performance panel or using third-party RUM monitoring — CrUX data provides the field measurement but not the attribution.