Why Core Web Vitals Matter in 2025: Understanding INP and the Future of Web Performance
In the modern web landscape, speed and responsiveness aren't just nice-to-have features—they are essential. Google's Core Web Vitals (CWV) define the key performance metrics that directly impact user experience and SEO rankings. And in March 2024, Google is introducing INP (Interaction to Next Paint) as a replacement for FID (First Input Delay), signaling a major shift in how interactivity is measured.
What Are Core Web Vitals?
Core Web Vitals are a set of user experience metrics that Google considers crucial for website performance:
- Largest Contentful Paint (LCP) – Measures loading performance. Should be under 2.5 seconds.
- Cumulative Layout Shift (CLS) – Measures visual stability. Should be below 0.1.
- First Input Delay (FID) (Soon Replaced by INP) – Measures interactivity. Should be under 100ms.
🚨 New in 2024: FID is being replaced by Interaction to Next Paint (INP), a more accurate interactivity metric.
INP: The Evolution of Interactivity Metrics
Why Replace FID?
FID only measures the delay of the first user interaction, which often doesn't reflect the real-world experience. INP, on the other hand, evaluates all interactions throughout a session and picks the worst one.
How INP Works:
- INP considers clicks, taps, and keyboard inputs.
- It measures the latency from interaction until the next visible update.
- Google suggests under 200ms for a "good" score.
| Metric | Good | Needs Improvement | Poor |
|---|---|---|---|
| TTFB | ≤ 800ms | 800ms - 1.8s | > 1.8s |
| LCP | ≤ 2.5s | 2.5s - 4s | > 4s |
| CLS | ≤ 0.1 | 0.1 - 0.25 | > 0.25 |
| INP | ≤ 200ms | 200ms - 500ms | > 500ms |
| FCP | ≤ 1.8s | 1.8s - 3s | > 3s |
| FID | ≤ 100ms | 100ms - 300ms | > 300ms |
Why Core Web Vitals Matter for SEO & UX
- Direct Impact on Google Rankings 📈 – Pages with better CWV scores rank higher.
- Better User Retention 🏆 – Fast, stable pages reduce bounce rates.
- Higher Conversion Rates 💰 – Performance optimizations can increase sales and engagement.
"53% of users abandon a site that takes longer than 3 seconds to load." – Google
How to Optimize for INP and Core Web Vitals
1. Optimize JavaScript Execution 🚀
- Minimize main thread work.
- Reduce third-party scripts.
2. Improve Event Handling ⚡
- Avoid long-running event listeners.
- Use requestIdleCallback for non-urgent tasks.
3. Reduce Layout Shifts (CLS) 🎯
- Define image dimensions (
height). - Use font-display: swap to prevent FOIT (Flash of Invisible Text).
4. Optimize Rendering Performance 🎨
- Avoid multiple renders (states granularly)
- Use CSS will-change for animations.
- Reduce DOM size and avoid excessive re-renders.
Final Thoughts: Are You Ready for INP?
With Google rolling out INP as the new interactivity metric, developers must rethink their performance strategies. Prioritizing responsiveness and optimizing for CWV is no longer optional—it's essential for SEO success and user engagement.
Resources & Further Reading
What's Your INP Score? 🤔
Have you checked your site's performance using Lighthouse or PageSpeed Insights?
I encourage you to check your INP and start measuring it to enhance the user experience on your website.