Response Time Checker / Glossary
HTTP/2 and HTTP/3
HTTP/2 sends many requests over one connection at once; HTTP/3 does the same over QUIC, which avoids head-of-line blocking and connects faster on lossy networks. Both matter most for pages with many resources.
How we measure it
We check whether the server offers h2 over ALPN and whether it advertises HTTP/3 in Alt-Svc.
What good looks like
h2 offered everywhere; h3 advertised by most CDNs.
How to improve it
- Enable HTTP/2 on the web server (nginx: http2 on;) or the CDN.
- Turn on HTTP/3 at the CDN where offered.
Measure your site
Three cold samples, every phase, and a diagnosis of what is slow.
Open the Response Time Checker