INP Optimization: Two Years After Core Web Vitals Update

Interaction to Next Paint (INP) replaced First Input Delay (FID) as a Core Web Vital in March 2024. Two years later in May 2026, only 64% of sites pass the 200ms ‘good’ threshold according to Chrome User Experience Report data. INP measures the latency of all user interactions during a page visit, exposing JavaScript-heavy sites and third-party script bloat that FID’s first-input-only measurement hid.

INP vs FID: Why the Change Happened

FID measured only the first input delay on a page, which often understated real performance issues. A page could pass FID but feel sluggish on every subsequent interaction. INP measures all interactions and reports the longest delay (excluding outliers), giving a more honest performance picture.

Per web.dev’s INP documentation, the ‘good’ threshold is 200ms or less. ‘Needs improvement’ is 200 to 500ms. ‘Poor’ is over 500ms. Google uses the 75th percentile of real-user INP across all interactions on a page.

The shift exposed sites that had optimized only for the first interaction. Sites with heavy single-page-app frameworks, complex modal systems, or interactive widgets saw INP scores 2 to 4x worse than their FID scores.

Current INP Performance Across the Web

Per Link Graph’s May 2026 Core Web Vitals report based on CrUX data, 64% of sites pass the 200ms INP threshold on mobile. This is up from 51% at INP launch in March 2024 but still leaves significant headroom.

Performance varies sharply by industry. News sites pass at 78% (lighter pages, fewer interactions). E-commerce sites pass at 42% (heavy checkout flows, third-party scripts). B2B SaaS marketing sites pass at 71%. Application interfaces pass at 38%.

Quick SEO’s analysis found the gap between mobile and desktop INP averages 87ms (desktop better). Mobile INP failures are concentrated in sites built with React, Vue, or Angular without performance budgets.

The Three Components of INP

INP measures total interaction latency in three phases: input delay (time before the event handler runs), processing time (time the event handler takes), and presentation delay (time to render the resulting paint).

Per web.dev’s INP breakdown documentation, presentation delay typically dominates on poorly performing sites because rendering blocks on layout thrash, large DOM updates, or expensive style recalculations.

Diagnose which component dominates by using Chrome DevTools Performance panel. Record an interaction, then examine the resulting trace for long tasks, layout shifts, and rendering work. Address the dominant component first.

Top Five INP Optimization Tactics

First, defer non-critical JavaScript. Use the defer or async attributes on script tags, and lazy-load any JavaScript not needed for above-the-fold content. This reduces main thread work during initial interactions.

Second, audit third-party scripts. Per Quick SEO’s INP analysis, third-party scripts cause 41% of INP failures. Use Google Tag Manager’s load priority settings, and remove scripts that do not justify their performance cost.

Third, break up long tasks. Any JavaScript task over 50ms blocks user interactions. Break long tasks using setTimeout, requestIdleCallback, or scheduler.yield() to give the browser time to handle interactions between work chunks.

• Defer non-critical JavaScript with defer/async attributes
• Audit and remove or delay third-party scripts (analytics, chat widgets, ad tags)
• Break long tasks into chunks under 50ms using scheduler.yield() or setTimeout
• Use CSS containment to isolate layout calculations to specific elements
• Replace heavy JS interactions with CSS animations where possible
• Implement code splitting so each route loads only required JavaScript

Diagnosing INP Issues with Chrome DevTools

Open Chrome DevTools Performance panel. Click record, perform the interaction (click a button, open a modal), then stop recording. Look for the interaction in the timeline (marked with a blue diamond) and examine the resulting tasks.

Per web.dev’s INP debugging guide, the Web Vitals extension also reports live INP values as you interact with a page. Install it, browse your site, and identify which interactions exceed 200ms.

For production monitoring, use Real User Monitoring (RUM) tools like SpeedCurve, Calibre, or Cloudflare Web Analytics. These capture INP across real user sessions, exposing issues that lab tests miss.

INP and SEO Ranking Impact in 2026

INP is a Core Web Vital, which means it factors into Google’s page experience signals. The ranking impact is modest (Google describes it as a tiebreaker), but the user experience impact is substantial.

Link Graph’s correlation study found that sites improving from ‘poor’ to ‘good’ INP saw an average 12% lift in organic conversion rate. The lift comes primarily from reduced bounce on slow interactions, not from direct ranking changes.