Originally published at shehrozaftab.com.
Google's Core Web Vitals are still part of how it judges page experience, and the biggest recent change catches out a lot of stores: INP replaced FID. If your Shopify or WordPress site felt fine on the old metric but now shows warnings, this is usually why.
The three Core Web Vitals in 2026
- LCP (Largest Contentful Paint): how fast the main content loads. Good is 2.5s or less.
- INP (Interaction to Next Paint): how quickly the page responds to taps and clicks across the whole visit. Good is 200ms or less.
- CLS (Cumulative Layout Shift): how much the layout jumps around. Good is 0.1 or less.
Why INP is stricter than the old FID
The retired metric, FID (First Input Delay), only measured the delay on your very first interaction, and only the input delay part. It was easy to pass even when a site felt laggy.
INP is tougher on purpose. It looks at interactions throughout the whole visit, not just the first, and it measures the full time until the page visually responds, not just the initial delay. So heavy JavaScript, bloated theme scripts and third-party tags that used to slide past FID now show up clearly.
What tends to hurt INP
On real Shopify and WordPress sites, the usual culprits are:
- Too much JavaScript running on the main thread, especially from apps and plugins you installed and forgot.
- Heavy third-party tags: chat widgets, popups, analytics, ad and tracking scripts all competing for the browser.
- Page builders and app blocks loading scripts sitewide even on pages that do not use them.
- Large, unbroken tasks that block the browser from responding while they run.
How I get sites back into the green
The approach is the same on both platforms, tuned to each:
- Audit what is loading. Measure with real field data (Chrome UX Report / Search Console), not just lab tests, because INP is about real interactions.
- Cut the JavaScript. Remove unused apps and plugins, defer non-critical scripts, and stop loading things on pages that do not need them.
- Tame third-party tags. Load chat, popups and analytics after interaction or on idle, not on first paint.
- Fix LCP and CLS alongside it. Optimise the hero image, reserve space for images and embeds, and use font-display: optional so text does not jump.
- Re-measure in the field over the following weeks, since Core Web Vitals use a rolling 28-day window of real users.
The takeaway
INP rewards sites that stay responsive the whole time someone is using them, not just on the first tap. For most Shopify and WordPress stores the fix is less code, fewer competing scripts, and disciplined third-party tags. Get those right and page experience stops being a drag on your rankings.
Seeing INP or Core Web Vitals warnings in Search Console? Send me your site and I'll audit it and lay out exactly what to fix.