Check your site's speed on the Performance page
See how fast and stable your site is for real visitors: Core Web Vitals from Chrome's report, or measured by the Zalify Pixel across every browser, with your slowest pages.
The Performance page shows how fast and stable your site is for real visitors. It reports Google's Core Web Vitals, the same measures Google uses to judge page experience, from two sources:
- Chrome report (CrUX): Google's own data from Chrome users, available for any public site with enough traffic.
- Zalify measured: collected by the Zalify Pixel from every visit, in every browser, on sites where the Pixel runs.
Open the Performance page
Go to Performance
In Zalify, open Websites in the left sidebar, then choose Performance under Data.
Pick a site
Choose one of your sites: a Zalify site, your Shopify store, or a site you added in Pixel. To check another site or a single page, type its address and click Check.
Choose a data source
If the Zalify Pixel has sent measurements from your site in the last 7 days, a Data source switch appears. Choose Chrome report (CrUX) or Zalify measured.
The five metrics
Each value is the 75th percentile: three in four visits do at least this well.
| Metric | What it measures | Good | Poor |
|---|---|---|---|
| Loading (LCP) | How long until the main content shows | ≤ 2.5 s | > 4 s |
| Responsiveness (INP) | How quickly the page reacts to taps and typing | ≤ 200 ms | > 500 ms |
| Visual stability (CLS) | How much content jumps around while loading | ≤ 0.1 | > 0.25 |
| First content (FCP) | How long until anything shows | ≤ 1.8 s | > 3 s |
| Server response (TTFB) | How long your server takes to start answering | ≤ 0.8 s | > 1.8 s |
Values between the two limits are rated Needs improvement. LCP, INP and CLS are the three Core Web Vitals; FCP and TTFB help explain a slow LCP.
Chrome report (CrUX)
- Covers Chrome users only, over a rolling 28 days.
- Splits results into Phone and Desktop, with the Share of visits in each rating and a Weekly trend.
- Works for any public site, including competitors, but only once Chrome has enough real visits. Otherwise you'll see No Chrome data for this site yet.
Zalify measured
- Covers every browser on sites running the Zalify Pixel, for the dates you pick: the last 7, 30 or 90 days.
- Filter by site (All sites or one) and by device.
- Each metric card shows how many visits it's based on.
- Daily trend plots the 75th percentile day by day.
- Slowest pages lists your most-visited pages, slowest to load first, so you know where to start.
- By device compares phone, desktop, tablet and other devices.
On the free plan, data covers the last 30 days. The 90-day range needs a paid plan.
Why the two sources never match exactly
The Chrome report covers Chrome users only, over a rolling 28 days. Zalify measured covers every browser, for the dates you pick. Use either one to follow a trend; don't expect the same numbers.
Turn on Zalify measured
Zalify measured needs the Zalify Pixel running on your pages. There's nothing else to set up: the Pixel starts measuring on its own.
- Shopify: turn on the Zalify Pixel app embed in your theme. Zalify's app pixel in Shopify Customer events runs outside the page, so it can't measure page speed. See Install the Zalify Pixel on Shopify.
- Other sites: add the Pixel snippet. See Add the Zalify Pixel to your site.
The Pixel sends one small report per page view, when the visitor leaves or hides the page, so it doesn't slow the page down. Measuring adds no cookies. Visits from known bots are left out.
Troubleshooting
- No Data source switch. The Pixel hasn't sent measurements from your site in the last 7 days. Check the Pixel is installed, then come back after your site has had some visits.
- A metric shows No data. There weren't enough visits in the period to work it out. Pick a longer range or All devices.
- INP is missing for a page. INP needs the visitor to tap, click or type. Pages people only read may not have enough interactions.