Google’s Core Web Vitals have become essential performance metrics for website owners, developers, and SEO professionals. With the arrival of 2025, one of the biggest updates to this framework is the introduction of INP (Interaction to Next Paint) as a replacement for FID (First Input Delay). This shift marks an evolution in how user experience is measured—particularly in terms of responsiveness. In this article, we’ll break down what’s new with Core Web Vitals in 2025, explain what INP is, and guide you on how to identify and fix INP issues to maintain your website’s performance and rankings.
What Is INP and Why Did It Replace FID?
INP (Interaction to Next Paint) is a metric that measures the latency between a user’s interaction (for example, clicking a button) and the next time something visibly changes on the page in response.
Previously, Google used FID (First Input Delay), which focused only on the delay before the browser was able to begin processing the first interaction. However, FID didn’t reflect the full user experience. INP was introduced to provide a more complete and accurate measurement of responsiveness across all interactions—not just the first one.
In short, while FID measured “when execution starts,” INP measures “when users actually see the result.”
What Does INP Measure Specifically?
INP tracks all interactions on a page (such as clicks, keyboard events, and taps) and records the time from initiation to the next visual change on the screen. Google then selects a representative interaction value (usually the longest) to report as the page’s INP score.
The performance thresholds are:
- Good: INP ≤ 200ms
- Needs Improvement: 200ms < INP ≤ 500ms
- Poor: INP > 500ms
Core Web Vitals 2025: What Else Has Changed?
The most notable update in the 2025 Core Web Vitals rollout is the official adoption of INP as a ranking signal in place of FID, starting in March 2025. However, that’s not the only tweak. Here’s a summary of what’s different:
- FID has been deprecated: Sites now rely entirely on INP for responsiveness metrics.
- CLS (Cumulative Layout Shift) remains a key metric, but now includes better support for tracking layout shifts caused by ads and infinite scroll elements.
- LCP (Largest Contentful Paint) thresholds remain the same, but tools like PageSpeed Insights now give even more detailed breakdowns for mobile and desktop separately.
- Real User Metrics (RUM): Emphasis has increased on gathering field data over lab data to provide more meaningful diagnostics.
How to Measure INP in 2025
To optimize for INP, you must first measure it accurately. Google provides several tools to gather INP data:
- Chrome User Experience Report (CrUX): Offers real-user metrics across thousands of websites.
- PageSpeed Insights: Now highlights INP scores with practical suggestions for improvement.
- Web Vitals JavaScript Library: Ideal for embedding directly into your site to capture field data.
- Lighthouse (Lab Data): Provides simulated performance, including INP estimations.
Why Does INP Matter for SEO?
Since March 2025, INP has become an official ranking factor. This means that sluggish and unresponsive websites could start seeing dips in search rankings. Given Google‘s push toward user-centric performance, optimizing INP is no longer “nice to have”—it’s a necessity.
Moreover, with more users accessing websites from mobile devices with varying network speeds, fast interaction performance can make or break your bounce rate and conversions.
Common Causes of Poor INP
Many websites struggle with INP because of the following culprits:
- Heavy JavaScript execution: Pages that run large JavaScript bundles can freeze the UI thread.
- Event listeners doing too much: Interaction handlers that trigger slow async operations or multiple reflows.
- Poorly optimized DOM updates: Making too many changes to the DOM without batching or throttling them.
- Third-party scripts: Trackers, widgets, and ads can pack in performance baggage.
How to Fix INP Issues
Fixing INP begins by identifying the bottlenecks. Here are some actionable strategies:
1. Optimize JavaScript Execution
Break up long tasks using requestIdleCallback or setTimeout() to avoid blocking the main thread. Use code-splitting to reduce the initial payload and eliminate unused code.
2. Use “passive” Event Listeners
Passive event listeners improve scrolling performance on touch and wheel with passive: true. Also, avoid placing logic-heavy operations in event handlers.
3. Minimize Layout Thrashing
Avoid triggering repeated reflows and repaints in your interaction handlers. Use techniques like batch DOM updates and work with virtual DOM libraries that help reduce layout churn.
4. Defer Non-Essential Scripts
Load third-party scripts like chat plugins or analytics tools after the main content has rendered. Always test their impact using Lighthouse or WebPageTest.
5. Prioritize Visual Feedback
If an interaction takes time, provide immediate visual feedback such as a spinner or state change. That way, even if the background process takes a while, the user knows their action has registered.
Bonus Tips for Front-End Developers
If you’re a developer working to optimize INP, here are some extra techniques to consider:
- Use Web Workers: Offload computationally expensive tasks to separate threads.
- Lazy load third-party widgets: Don’t let social embeds or ads bottleneck the user interaction flow.
- Implement Abort Controllers: Cancel outdated processes when a new interaction takes priority.
- Monitor field performance: Continuously gather real-user metrics using RUM tools like SpeedCurve or Calibre.
What Google’s Documentation Recommends
Google suggests maintaining a consistent UI thread performance budget of less than 50ms per task. The idea is to keep all tasks short so they don’t block the interaction pipeline. They also recommend tools like Web.dev INP Guide for developers to follow best practices when optimizing interactivity.
Preparing for the Future
As the web continues to evolve, metrics like INP will become even more nuanced. Google has already hinted at the next generation of user-perceived performance metrics, which might include things like smoothness, predictability, or even “delight” factors in interaction. Staying updated and being proactive about performance is key.
Working with modern frameworks like React 18, Vue 3+, or Svelte offers built-in features that can help manage rendering pipelines more efficiently—assuming you configure them wisely. Leveraging framework-specific performance modules will be increasingly crucial for teams building complex web applications.
Conclusion
INP is more than just another metric—it’s a paradigm shift in how we measure and think about user interaction. By focusing on the visual responsiveness of all interactions—not just the initial one—it offers a far more realistic picture of the user experience. With its integration into Core Web Vitals in 2025, INP is now a major player in both performance and SEO.
If your site is still relying on old performance optimization tactics, it’s time to pivot, test, and tune. With the right strategies and tools, ensuring a solid INP score is not only possible—it’s a competitive advantage in the ever-changing digital landscape.