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Free performance check

Page Speed Test and Core Web Vitals Checker

Measure how fast a page answers and renders on a throttled mobile profile, and find the causes: heavy pages, missing compression, uncached assets and render blocking scripts.

Test page speed

Enter a page. It is loaded in a headless browser on a throttled mobile profile.

Runs 9 checks. A bare domain works, https:// is added for you. The timings are lab measurements from one region and one device profile. Field data from real visitors, as in the Chrome UX Report, can differ.

Checks in this tool:perf.ttfbperf.lcpperf.clsperf.tbtperf.page-weightperf.compressionperf.cachingperf.image-formatsperf.render-blocking

Why use the Page Speed Test

Core Web Vitals

Largest Contentful Paint and Cumulative Layout Shift, with Total Blocking Time as the lab stand in for Interaction to Next Paint.

Server response

Time to first byte is measured directly, the part of the load that only your server and CDN control.

The causes

Page weight, compression, cache headers, image formats and render blocking resources explain the timings.

No guessing

When no browser is available the rendered metrics are reported as skipped with the reason, never estimated.

When to use the Page Speed Test

Before and after

Measure a change to a template, a plugin or a CDN setting.

Slow pages

Find out whether the server, the assets or the scripts are the problem.

Hosting comparisons

Compare time to first byte across hosting and CDN setups.

Third party scripts

See how much tags, chat widgets and ads cost.

Mobile experience

The throttled profile shows what a mid range phone on a slow network gets.

Monitoring

Track the numbers over time with a monitor and catch regressions.

Understanding Page Speed

The metrics

  1. 1TTFB. Time until the first byte of the response. Good is under 0.8 seconds.
  2. 2LCP. When the largest element in view is painted. Good is under 2.5 seconds.
  3. 3CLS. How much the layout moves while loading. Good is under 0.1.
  4. 4TBT. How long the main thread is blocked between paint and interactivity. Good is under 200 milliseconds.

Lab data and field data

This test is a lab measurement: one load, one region, one simulated device. It is repeatable and good for finding causes. Field data, from real visitors over 28 days, is what Google uses in search. If your site has enough traffic, compare with the Chrome UX Report or Search Console.

Expect variance between runs. Look at large differences and at trends, not at a few milliseconds.

Where to start

A slow TTFB points at the server, the database or a missing cache. A slow LCP with a fast TTFB points at large images or render blocking resources. A high TBT points at too much JavaScript. Layout shift points at images and embeds without reserved space.

Privacy, safety and limits

The page is loaded by a headless browser on Cloudflare's network with the AbackAuditBot identity. No cookie or login is used, so pages behind a login are not measured.

Related tools and guides

Image SEO CheckerImages without alt text are invisible to screen readers and image search. Oversized and legacy images slow the page down. Check both in one go.Accessibility CheckerFind the accessibility problems that automated testing can catch reliably: missing labels, unnamed buttons, broken ARIA, missing landmarks and text that is hard to read.JavaScript SEO CheckerMany crawlers, including most AI crawlers, read the HTML the server sends and never run your JavaScript. Check how much of the page they actually see.SEO CheckerFind the technical problems that keep a page out of search results. The checker reads the page the way a search crawler does and lists what to fix first, with the evidence behind every verdict.Security Headers CheckerSecurity headers tell browsers to stay on HTTPS, refuse to be framed, stop guessing content types and limit what scripts may do. Check which ones your site sends and how they are set.Redirect CheckerFollow every redirect of an address, hop by hop. Find chains that slow crawlers down, loops that break pages, and host variants that split your signals across duplicates.Guide: Core Web Vitals explainedWhat Largest Contentful Paint, Cumulative Layout Shift and Interaction to Next Paint measure, the thresholds, the difference between lab and field data, and the fixes that move each metric.

Frequently asked questions

Is this the same as PageSpeed Insights?

It measures the same kind of lab metrics with a similar throttled profile, but from Cloudflare's network. PageSpeed Insights also shows field data from the Chrome UX Report when your site has enough traffic.

Why is INP not measured?

Interaction to Next Paint needs real interactions. Total Blocking Time is the lab metric that correlates with it.

Why do my numbers change between runs?

Network conditions, server load and third party scripts vary. Run the test a few times and look at the range.

Why are some metrics skipped?

Rendered metrics need a headless browser. When none is available the test reports them as skipped with the reason instead of guessing.

Does speed affect rankings?

Core Web Vitals are part of Google's page experience signals. They matter most when competing pages are otherwise similar, and they always matter to visitors.

What is a good page weight?

Under about 1.5 MB is a reasonable target for most pages. Images and JavaScript are usually the largest parts.

Can I test from another country?

Not yet. The test runs from Cloudflare's network near the audit worker.

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