How to Improve Your Site's INP Score for Better User Experience

Google's Core Web Vitals now include Interaction to Next Paint (INP) as a key metric for measuring a page's responsiveness. INP assesses the time from when a user interacts with your page (like clicking a button or tapping a link) to when the browser responds visually. A good INP score is 200 milliseconds or less. Poor INP can frustrate users and hurt your search rankings. Here's how to diagnose and fix INP issues.

What Causes High INP?

High INP usually stems from long tasks on the main thread that block the browser from responding quickly to user input. Common culprits:

• Heavy JavaScript execution (e.g., complex frameworks, large libraries)
• Inefficient event handlers (e.g., handlers that do too much work)
• Large DOM updates triggered by interaction
• Third-party scripts (analytics, ads, widgets) that run on input

Step 1: Measure Your INP Score

Before optimizing, you need data. Use Chrome DevTools Performance panel to record interactions and see the main thread activity. Also check your real-user data in Google Search Console under Core Web Vitals. Run a free audit of your site with MyWebsiteScore to get a prioritized list of performance issues.

Step 2: Identify Long Tasks

Open Chrome DevTools, go to Performance, and start recording. Interact with your page (click, tap, type). Stop recording and look for long tasks (tasks taking more than 50ms). Each long task can delay INP. The Long Tasks API can also help monitor this programmatically.

Step 3: Break Up Long Tasks

If you see tasks over 50ms, break them into smaller chunks. Use setTimeout() or requestIdleCallback() to defer non-urgent work. For example, if a click handler processes a large list, split it into batches:

function handleClick() {
  // Critical UI update first
  updateUI();
  // Defer heavy processing
  setTimeout(() => processData(), 0);
}

Step 4: Optimize Event Handlers

Keep event handlers lean. Avoid running expensive operations directly inside handlers. Move heavy logic to a separate function that runs asynchronously. Debounce or throttle events like scroll or resize to reduce frequency.

Step 5: Use Web Workers for Heavy Tasks

Offload CPU-intensive work (like data parsing or image processing) to a Web Worker. This runs on a separate thread, keeping the main thread free for user interactions.

const worker = new Worker('worker.js');
worker.postMessage(data);
worker.onmessage = function(e) { /* handle result */ };

Step 6: Defer Third-Party Scripts

Third-party scripts often cause INP issues. Load them asynchronously with async or defer attributes. If possible, load them only after user interaction. Use the IntersectionObserver to lazy-load widgets when they come into view.

Step 7: Minimize DOM Size and Reflows

Large DOM trees and frequent layout changes can make interactions slow. Use CSS contain property to isolate parts of the page. Batch DOM updates and avoid forced reflows by reading layout properties after writes.

Step 8: Test and Monitor

After making changes, test again with DevTools and real-user monitoring. Check your INP score in Search Console. Continue to iterate. Remember, INP is about perceived responsiveness—every millisecond counts.

Conclusion

Improving INP is crucial for user satisfaction and SEO. Focus on breaking up long tasks, optimizing event handlers, and reducing main-thread load. Run a free audit of your site to identify other performance bottlenecks that may affect INP and other Core Web Vitals.

For more guides on website optimization, visit our guides library. Start improving your INP today—run a free audit of your site.

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