Interaction to Next Paint

What this check looks for

For pages with measured field performance data, this check grades INP — the delay between a visitor's interaction (a click, tap, or keypress) and the next visual update reflecting it — against Google's thresholds: at or under 200ms passes, between 200 and 500ms warns, and beyond 500ms fails. This metric is field data only, meaning it requires real visitor interactions to measure; pages without that data report "na".

Why it matters

INP replaced First Input Delay as a Core Web Vital because it measures responsiveness across the entire page visit, not just the very first click — a page that feels snappy on first load but sluggish on every subsequent interaction (a filter dropdown, a form field, an "add to cart" button) still fails the experience visitors actually notice most. Slow interaction response is usually caused by long-running JavaScript tasks blocking the main thread exactly when a visitor tries to act, which is a frustrating, tangible kind of slowness rather than an abstract loading-time number. As a confirmed Core Web Vital, INP directly factors into how Google evaluates page experience for ranking.

How to fix it

Break up long JavaScript tasks and defer non-critical work so the main thread stays free to respond to input:

// Long synchronous task blocks input handling
function renderResults(items) {
  items.forEach(renderRow); // thousands of rows, all at once
}

// Fixed: yield to the main thread between chunks
async function renderResults(items) {
  for (const chunk of chunkArray(items, 50)) {
    chunk.forEach(renderRow);
    await new Promise((r) => setTimeout(r, 0));
  }
}

Also defer non-critical third-party scripts (analytics, chat widgets) so they don't compete with user-triggered work for main-thread time.