How to Check Your WordPress Website's Performance

A slow website quietly costs you visitors, enquiries, and search ranking — and most owners only notice once the damage is done. The good news: you can check your WordPress site in about ten minutes, for free, without touching any code. Here's what to open, what to look at, and what to ignore.

Step 1: Run PageSpeed Insights (5 minutes)

Start at Google PageSpeed Insights. Paste your homepage URL and one page that matters to your business — a services page, a booking page, a product page. Test both, on Mobile first (that's where most of your visitors are) and then Desktop.

You'll get two very different kinds of result on the same screen, and understanding the difference is the single most useful thing in this guide.

Field data vs lab data

Field data — the section at the top labelled "Discover what your real users are experiencing" — comes from Chrome's User Experience Report (CrUX). It's what actual visitors experienced on your site over the last 28 days, and it's judged at the 75th percentile: your page passes only if three out of four visits hit the target. This is what Google uses when it thinks about your search ranking.

Lab data — the score out of 100 and the "Diagnose performance issues" section below it — is one simulated visit run by Lighthouse on Google's servers, on a throttled connection. It's useful for spotting what to fix, but it's a single test under artificial conditions.

Owners routinely panic about a lab score of 55 while their field data is green — or relax about a 95 while real visitors are struggling. When you have field data, trust it over the score. Small sites sometimes lack the traffic for CrUX to report anything; then the lab numbers are all you've got, so run the test two or three times and go by the consistent result.

The three numbers that count

Ignore the big score for a moment and look at the Core Web Vitals — the three measurements Google uses to judge how a page feels:

If you've read an older guide, you may see First Input Delay (FID). It was retired in March 2024 and replaced by INP, which is a tougher, more honest measure of responsiveness. Any tool still showing FID is out of date. For a plain-language walkthrough of each metric, see our intro to Core Web Vitals.

One more number worth knowing: TTFB (Time to First Byte) — how long the server takes to start sending the page. A slow TTFB points at hosting or server configuration, not your content, and it drags every other metric down with it.

Step 2: Check Search Console (3 minutes)

PageSpeed Insights shows one page at a time. To see your whole site the way Google sees it, open Search Console and go to Experience → Core Web Vitals. It groups your URLs into Good, Needs Improvement, and Poor, using the same field data, and shows you which pages are dragging you down. If you haven't set up Search Console, do it once — it's free, and it's Google's own report card for your site.

Other tools, when you need them

• Chrome DevTools — right-click any page → Inspect. The Lighthouse tab runs the same lab test locally; the Performance panel records a real load and shows what's slow.
• GTmetrix — a friendlier presentation of a Lighthouse test, with a waterfall chart that makes one oversized image or heavy script easy to spot.
• WebPageTest — the most detailed, with tests from different locations and connection speeds.

Older articles still recommend web.dev/measure; Google has retired it. PageSpeed Insights does the same job.

Don't forget uptime

Speed only matters if the site is actually up. Real performance monitoring includes something checking around the clock that your site is answering — and alerting someone when it isn't. That's not a job to do by hand.

What's yours, and what's your host's

You should test your two or three most important pages a couple of times a year, and glance at Search Console's Core Web Vitals report after any big change (new theme, new page builder, a redesign). Test on mobile, re-test before you trust a bad result, and fix the biggest thing first — usually an oversized image, a heavy builder, or slow hosting.

Your host should own the rest: server response time, caching, image delivery, PHP and database tuning, and uptime monitoring with alerts. That's where most of the real speed lives, and it's configuration work, not content work. At Site Schema we monitor uptime and performance for every site we host, so the metrics stay green without you opening a testing tool — but now you know how to check our work.