A web performance audit is a structured check of how fast and stable your website is, followed by a ranked list of fixes. To run one, pick your key pages, record a baseline with speed tests and real-user data, find the biggest causes of slowness, fix them in order of impact and re-test. Start your baseline with our free website speed test.
Key takeaways
- An audit needs a baseline first, so you can prove that your fixes worked.
- Use both lab data (a test) and field data (real visitors).
- Fix by impact, not by how easy a fix looks.
- Good targets are LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less (Google, web.dev).
What is a web performance audit?
A web performance audit measures how your site performs for real visitors, finds what slows it down and produces a prioritized action list. It is different from a single speed test, because it covers several pages, several metrics and the causes behind them.
How do you run a web performance audit?
1. Choose the pages to audit
Pick one page for each template: your homepage, a blog post or product page, a category page and your most important landing page. Add your highest-traffic pages.
2. Record a baseline
Test each page on mobile with our PageSpeed Insights walkthrough or our free page speed checker. Save the scores, the Core Web Vitals and the date. Run each test two or three times.
3. Check real-user data
Open the Core Web Vitals report in Google Search Console to see which page groups fail for real visitors. See our Core Web Vitals test guide.
4. Diagnose the causes
Use the waterfall and the report’s issues list to find what delays each page. The checklist below covers the usual causes.
5. Prioritize
Rank each issue by impact and effort. Fix high-impact, low-effort items first, such as oversized images or missing caching.
6. Fix and re-test
Change one thing at a time and re-test with the same tool and settings.
7. Document and monitor
Keep a simple log of what you changed and the result. See website performance monitoring tools.
What should the audit checklist include?
| Area | What to check | Where to learn more |
|---|---|---|
| Server | Server response time, caching, PHP version | Good TTFB |
| Images | Size, format, lazy loading, dimensions | Optimize images |
| Code | Unused JavaScript and CSS, render-blocking files | Render-blocking resources |
| Third parties | Ads, chat, trackers and popups | Why sites are slow |
| Main content | LCP element and what delays it | Fix LCP |
| Layout | Image sizes, banners and fonts that shift content | Performance metrics |
| Mobile | Mobile scores and real-user mobile data | Mobile page speed |
Which tools do you need for an audit?
- Quick tests: our free tool and Google PageSpeed Insights.
- Detail: WebPageTest for waterfalls. See how to use WebPageTest.
- Real users: Search Console’s Core Web Vitals report.
- Debugging: Chrome DevTools Lighthouse.
How do you report audit results?
List each page, its baseline and after-fix scores, the issues found, what you changed and what is still open. Keep it short and show the improvement in Core Web Vitals, not only the PageSpeed score.
How often should you audit your website?
Run a full audit once or twice a year and a quick check after every major theme, plugin or design change.
Frequently asked questions
What is the difference between a speed test and an audit?
A speed test measures one page. An audit covers several pages, finds causes and gives a prioritized fix list.
How long does a performance audit take?
A small site can be audited in a few hours. Larger sites take longer.
Do I need a developer for an audit?
Not to run one. You may need help for some fixes, such as removing leftover code.
What is a good audit result?
Passing Core Web Vitals on your key pages, with a mobile PageSpeed score of 90 or above as a guide.
Can I do an audit for free?
Yes. Free tools such as PageSpeed Insights, Search Console and our speed test cover most of it.
Conclusion
A web performance audit is a baseline, a diagnosis, a ranked list and a re-test. Start with our free website speed test, and follow our guide on how to improve website speed to fix what you find.
