“Is my store fast?” sounds like a simple question. For WooCommerce it is not, because a store is not one page. A fast home page can sit in front of a slow checkout, and a score that looks good in a test can hide what real customers on phones experience. This guide shows how to measure properly and how to read what you find.
Test the pages that earn money, not just the home page
Test at least these, separately:
- The home page.
- A category or shop page with many products.
- A single product page.
- The cart, and the checkout.
Cart and checkout matter most. They are dynamic, they usually cannot be cached the way the rest of the site is, and a delay there costs sales directly.
Step 1: run PageSpeed Insights
Go to Google’s PageSpeed Insights and enter a page address. Run it for each page above, and look at the mobile result first, because most shoppers are on phones.
The report has two parts that people often mix up:
- Field data (“Discover what your real users are experiencing”): measurements from real Chrome visitors over the previous 28 days. This is what Google uses, and it only appears if the page has enough visits.
- Lab data (the score and “Diagnose performance issues”): a single simulated test run now. It is useful for finding causes, but it can vary from one run to the next, so run it a few times and do not chase one number.
If field data is missing, your page does not have enough traffic for Google to report on it. Use lab data to find problems and treat the score as a guide.
Step 2: understand the three measures that matter
Google’s Core Web Vitals judge three things. A page is “good” when at least 75% of visits meet the threshold.
| Measure | What it tells you | Good |
|---|---|---|
| LCP (Largest Contentful Paint) | How long until the main content, usually the main image or heading, is visible. | 2.5 seconds or less |
| INP (Interaction to Next Paint) | How quickly the page responds when someone taps or clicks. | 200 milliseconds or less |
| CLS (Cumulative Layout Shift) | How much the page jumps around while loading. | 0.1 or less |
Step 3: look at the slow parts
The PageSpeed report lists opportunities. For WooCommerce stores, the same few causes show up again and again:
- Large images in product galleries and banners, especially the first image on the page (a common cause of slow LCP).
- Too much JavaScript from many plugins loading on every page, which hurts INP.
- Slow server response, from weak hosting, no object cache or a heavy database.
- Elements without reserved space, such as banners, cookie notices and late-loading fonts, which cause layout shift.
Step 4: find which plugin is responsible
If the page is slow and you do not know why, a profiling tool such as Query Monitor shows which plugins add database queries and time to each page. Test on a staging copy: disable a plugin, measure again, and compare. Change one thing at a time so you know what made the difference.
Step 5: check in Search Console
If your store has enough visitors, the Core Web Vitals report in Google Search Console groups your pages as Good, Needs improvement or Poor, based on real visits. It is the best view of how Google sees your site as a whole, and it updates slowly, so allow weeks for a fix to show.
What a test cannot tell you
- A single test is one visit from one place. Real customers have slower phones and weaker connections.
- Speed changes over time. A new plugin, a bigger catalogue or a marketing banner can undo earlier gains.
- A good score does not prove checkout works. A fast page can still fail to take payment.
Keeping watch without testing by hand
Testing by hand is fine for a one-off check, and it is easy to forget afterwards. Commerce Health PRO measures real-visitor checkout speed (LCP, INP and CLS) in the background and flags it when it gets worse, so a slow plugin update shows up soon after it is installed. It reports what visitors experience, but it cannot see your hosting limits or fix the cause for you. See how WooCommerce store health monitoring works.
If you have measured your store and the numbers are poor, and you would rather have the cause found and fixed, that is the work behind our WooCommerce performance optimisation service.