Page speed and Core Web Vitals

The Page speed tab runs Google PageSpeed Insights on any page of your site without leaving WordPress. You see the performance score, whether the page passes Core Web Vitals for real visitors, the lab metrics and the biggest opportunities to make it faster.

Speed is a ranking factor and a big part of how visitors experience your site. Core Web Vitals (loading, responsiveness and visual stability) are the metrics Google uses for it.

Run a test

1. Go to RankKit SEO → Site Audit → Page speed.
2. In URL to test, enter the page address. Leave it empty to test your home page.
3. Choose Mobile or Desktop under Device.
4. Click Run test.

Tests run on Google's servers and take 10 to 30 seconds. Nothing runs until you click. To test the same page again later, click Test again.

Read the results

Section	What it shows
Performance score	Lighthouse's 0 to 100 score for the page on the chosen device.
Passes Core Web Vitals / Fails Core Web Vitals	Whether real visitors had a good experience, from the Chrome UX Report.
Real users (Chrome UX Report, last 28 days)	Field data from Chrome users: Largest Contentful Paint, Interaction to Next Paint, Cumulative Layout Shift and Time to First Byte. A whole site badge means Google only has data for your site as a whole, not for this page.
Lab test (simulated)	A one-off test on Google's servers: Largest Contentful Paint, Total Blocking Time (which stands in for INP in a lab test), Cumulative Layout Shift, First Contentful Paint and Speed Index.
Biggest opportunities	The changes that would save the most time, with the estimated saving (for example "save ~1.2 s").
Score history	A chart of the page's earlier scores on the same device, once it has been tested more than once.
Tested pages	Every page you tested, with its Mobile and Desktop scores, real-user LCP and Last test time. Click a URL to show its results.

Each metric is rated Good, Needs improvement or Poor using Google's Core Web Vitals thresholds, for example Largest Contentful Paint is good up to 2.5 s and poor above 4 s.

If Google has no real-user data for your page or site yet, you see a message saying so. Small and new sites often have none. The lab results still show what to fix.

RankKit SEO keeps the history of up to 25 pages, with up to 30 runs each.

Settings

Administrators see PageSpeed settings at the bottom of the same tab.

Setting	Default	What it does
PageSpeed Insights API key (optional)	Empty	Without a key, tests use Google's shared quota and can be refused at busy times. A free key comes from Google Cloud Console → APIs → PageSpeed Insights API.
Test the home page every week	Off	Runs a mobile and desktop test of the home page once a week so the history fills in on its own.

Click Save after changing them.

Speed checks in the site audit

The site audit has its own Performance category. It does not use PageSpeed Insights; it checks your server and home page directly: response time, compression, page cache, page weight, render-blocking files, image sizes, browser caching, object cache and autoloaded options. Use both: the audit finds setup problems in seconds, PageSpeed Insights measures what visitors experience. See Every site audit check explained.

The home page's mobile speed also appears in the email report and in the WordPress dashboard widget.

FAQ

Why does my score change between tests?

Lab tests are a single simulated load, so network and server timing vary a little each run. Look at the trend in Score history and at the real-user data, which covers 28 days.

Do I need a PageSpeed Insights API key?

No. It is optional. Add one if tests are refused because the shared quota is busy, or if you test often.

Can an AI agent run speed tests?

Yes. Connected agents can use the pagespeed_run and pagespeed_report tools. See Connect an AI agent.

Troubleshooting

Problem	Cause	Fix
The test is refused or times out	Google's shared quota is busy, or the page took too long to load.	Add a PageSpeed Insights API key, then click Test again.
No real-user data	Not enough Chrome visitors in the last 28 days.	Use the lab results. Field data appears once the page or site has enough traffic.
The test fails for a staging or password-protected site	PageSpeed Insights runs on Google's servers and can only load public URLs.	Test the live site.