What the score covers
Server-side factors we can measure directly: response time, compression, HTTPS, security headers, and the SEO basics in your page’s HTML. A good score here is the foundation for good Core Web Vitals.
What it doesn’t cover
Real-browser rendering (images, JavaScript, layout shift). For that, also run Google’s Lighthouse at pagespeed.web.dev.
Frequently asked questions
You may be on a fast connection close to the server. Visitors elsewhere, and Google, see the server response time we measure.
Under 600 ms to first byte is good; under 200 ms is excellent. Caching usually makes the biggest difference.
Not directly, but HTTPS does, and the headers protect your visitors, which is part of being a trustworthy site.