Google employee Martin Splitt shared on Twitter the technical details of how the search engine measures the metrics that make up Core Web Vitals, reports SearchEngines.
He spoke about this, answering a question from one of the specialists. In particular, he asked:
“If Googlebot uses a non-Googlebot user-agent to check CLS, LCP and any other Web Vitals metrics, what would be its name? We’ve implemented dynamic rendering for Googlebot. Should anyone who has implemented dynamic rendering worry about poor Web Vitals for URLs in Search Console? ”
Answering the question, Martin Splitt immediately divided it into several parts:
- Googlebot takes measurements
- Dynamic rendering and performance
- Performance and UX
- Real users metrics (rUM) vs lab data
- Search Console Key Internet Metrics Report
Answers point by point:
1. Googlebot renders using Googlebot UA (user-agent). During rendering, some lab data can also be collected. However, this is not the full story yet. Don’t worry about non-Googlebot UA.
2. When you use dynamic rendering, you can create a slight delay while the renderer generates static HTML. You can work around this with caching and regular cache preheating. But the performance that Googlebot and the user will see will be different.
3. Therefore, it is important to remember that a) Google cannot simply rely on the site performance data that Googlebot collects; b) Your users may experience slow website performance, which will need to be fixed, since slow websites are bad for users.
4. Moving on to the measurements: Googlebot (or Lighthouse, or PageSpeed Insights) measures “lab data”, which is data on hypothetical performance in a fairly ideal environment. And that doesn’t match what real users see.
5. Therefore, Google Search Console considers a combination of lab data and real user data (rUM / Chrome UX Report) to identify performance signals.
6. The Chrome web baseline report shows limited data (since not every URL has enough rUM data), but these are real user metrics. Therefore, if something is “bad” here, it means that real users are suffering, and this definitely needs to be fixed.
NIX Solutions reminds that in May, Google replaced the Search Console speed report with a Core Web Vitals report that was released on May 5.
Note also that Web Vitals will be part of a new Page Experience ranking signal expected to launch in 2021.