On March 12, 2024, Google replaced First Input Delay (FID) with Interaction to Next Paint (INP) as one of its three Core Web Vitals. If you’ve opened Search Console in the past few weeks and seen new warnings about your store, this is probably why. Many sites that passed easily under FID are finding that INP is a harder test.

Here’s what INP measures, why WooCommerce stores often struggle with it, and the practical fixes you can make without becoming a developer.

What INP measures, in plain English

INP measures how quickly your page visibly responds when someone interacts with it: clicks a button, taps a menu, picks a size, types in a search box. It covers the time from the interaction until the browser paints the next frame showing a result.

The older metric, FID, only measured the delay before the browser started handling the first interaction on a page. INP is stricter in two ways:

• It looks at interactions throughout the whole visit, not just the first one.
• It measures the full time until the screen updates, not only the initial delay.

Google’s thresholds for INP are:

Like the other Core Web Vitals, your rating is based on real visitor data at the 75th percentile, so the experience of your slower visitors on slower phones counts.

Why it matters for an online store

Core Web Vitals are one of many signals Google uses for ranking, and they’re rarely the deciding factor on their own. The bigger reason to care is your customers.

A sluggish store feels broken. Someone taps “Add to cart” and nothing happens for a moment, so they tap again, and now there are two items in the cart. They choose a color and the image doesn’t change right away. They open the mobile menu and it hangs. Each of these is a small moment of doubt during a purchase, and doubt is what makes people leave.

How to check your store’s INP

Start with the tools that use real visitor data:

1. Google Search Console. The Core Web Vitals report now shows INP. It groups similar URLs together, so you can see if, for example, all product pages share a problem.
2. PageSpeed Insights. Enter a URL and look at the top section, which shows field data from the Chrome User Experience Report if your site has enough traffic.
3. Chrome’s Web Vitals extension. Install it, browse your own store, and click around. It shows the INP of your interactions as you go, which helps identify which button or widget is slow.

Note that the lab score in PageSpeed Insights (the Lighthouse part) doesn’t measure INP directly because no one is clicking during the test. Total Blocking Time in the lab report is a useful hint, though: a high number usually means INP will suffer too.

If your store is small, you may see “not enough data” for field metrics. In that case, use the Web Vitals extension on a mid-range phone or with CPU throttling turned on in Chrome DevTools to approximate what your visitors experience.

What typically slows WooCommerce stores down

INP problems almost always come down to JavaScript keeping the browser busy. When the main thread is running a long task, it can’t respond to a tap. On WooCommerce sites, the usual culprits are:

• Too many plugins loading scripts on every page. A form plugin, a slider, a chat widget, a reviews widget, several tracking tags, and each adds work.
• Heavy page builders and themes that ship large amounts of JavaScript and CSS whether a page needs it or not.
• Third-party scripts: analytics, ad pixels, heatmaps, social embeds, live chat.
• Sliders and carousels, especially on the home page and in product galleries.
• Complex variation selectors on variable products with many options, where every change triggers a lot of work.
• Very large pages with huge numbers of elements, such as category pages showing 100 products with quick-view buttons.
• AJAX add-to-cart and mini-cart updates that trigger expensive re-rendering.

Fixes you can make without a developer

1. Audit and remove plugins

Go through your plugin list and ask of each: is this still used, and does it need to run on every page? Deactivate what you don’t need. For plugins you keep, check their settings: many let you load scripts only on specific pages.

Test after each change. The Web Vitals extension makes it easy to compare before and after on the same page.

2. Cut back third-party scripts

Look at every tracking tag and widget. You may have pixels for ad platforms you stopped using months ago. Live chat widgets are useful but heavy; consider loading them only after a delay or only on key pages. If you use a tag manager, clean out old tags there too.

3. Rethink sliders and carousels

A home page slider looks nice but often does little for sales and a lot for load and interaction times. A single strong hero image with a clear call to action is usually faster and easier to understand. If you keep a slider, choose a lightweight one and limit the number of slides. Our older post on WooCommerce sliders covers the different types.

4. Choose a lighter theme

Your theme sets the baseline for every page. Some themes load large JavaScript libraries, animation frameworks and page-builder code everywhere. A theme built for performance, with modest scripts and good WooCommerce support, makes all your other optimizations easier.

When evaluating a theme, test its demo in PageSpeed Insights and click around its product pages with the Web Vitals extension running. That will tell you more than a marketing claim.

5. Simplify product pages

Product pages carry the most interactions: gallery, variations, quantity, add to cart, tabs, reviews. Ways to lighten them:

• Keep galleries lean and use properly sized images. Our guide to WooCommerce product images covers sizes and formats.
• Avoid stacking several “extras” widgets (countdown, sales notifications, size chart popup, chat) on the same page.
• For products with many variations, check that the swatches plugin you use is well maintained and not doing heavy work on each click.

6. Delay non-essential JavaScript

Many caching and performance plugins can delay non-critical scripts until the visitor interacts, or defer them so they don’t block the page. This can help a lot, but test carefully: delaying the wrong script can break a checkout button or a variation selector. Always test the full purchase path after changing these settings.

7. Load popups and widgets efficiently

Popups, chat and review widgets should load in a way that doesn’t compete with the page’s main interactions. When choosing any on-page marketing tool, check how much JavaScript it loads and whether it loads on pages where it isn’t shown.

A walkthrough: fixing a slow “Add to cart”

Here’s a hypothetical example. A store owner notices on her phone that tapping “Add to cart” on product pages feels slow. Search Console shows product pages in the “Needs improvement” group for INP.

1. Reproduce it. With the Web Vitals extension on and CPU throttling in DevTools, she taps “Add to cart” and sees an INP value well over 200 ms.
2. Look for suspects. The product page loads a slider, a size-chart plugin, a live chat widget, a reviews widget, and three ad pixels.
3. Remove one at a time. Disabling the unused ad pixels helps a little. Setting the chat widget to load only after a delay helps more. The biggest improvement comes from replacing a heavy slider-based gallery with the theme’s built-in gallery.
4. Test the whole flow. She checks that add to cart, variations, the cart page and checkout all still work.
5. Wait for field data. Search Console’s data is based on the last 28 days of visits, so it takes a few weeks to reflect the change. She uses “Validate fix” in the report and waits.

The lesson: the fix was mostly subtraction, not new tools.

What about hosting and caching?

Good hosting and page caching matter a lot for how fast a page first loads, which affects Largest Contentful Paint. But INP is mostly about what happens in the visitor’s browser after the page loads, so a faster server alone won’t fix it. You’ll get the most benefit by combining solid hosting with less JavaScript.

A faster store is a lighter store

INP rewards stores that do less work in the browser. That usually means fewer plugins, fewer third-party scripts, simpler product pages and a theme that doesn’t load everything everywhere. Start with the page type Search Console flags, find the slowest interaction, and remove what’s causing it one step at a time.

If you’re considering a theme change as part of this, iConvert Themes are built for WooCommerce stores and worth testing alongside other lightweight options.

Flavius Noja

Flavius is an online marketing specialist with experience in the digital field. He is passionate about everything that means the online world, sports, but also crypto.