HTML document protocol on React sites
HTTP/2, HTTP/3, or HTTP/1.1 on the main HTML document: how the protocol changes Time to First Byte (654 ms faster on HTTP/3) and how much comes from edge CDNs.
On React, 24.1% of sites serve their main HTML document over HTTP/2, 68.2% use HTTP/3 over QUIC, and 7.7% still use HTTP/1.1. On HTTP/3, 91% of React sites have a good LCP, against 66% on HTTP/2 and 83% on HTTP/1.1. In Chrome's field data, HTTP/3 cuts median Time to First Byte by 654 ms compared with HTTP/2 (422 ms against 1076 ms).
LCP pass rate
Sites serving their HTML over HTTP/3 (h3) have a good LCP most often at 91%, followed by HTTP/1.1 at 83% and HTTP/2 (h2) at 66%. HTTP/1.1 sits slightly ahead of HTTP/2 here because many HTTP/1.1 sites are small static pages. Six in seven HTTP/2 sites serve dynamic CMS pages straight from the origin server, while more than half of HTTP/3 sites sit behind an edge CDN.
HTML document protocol usage
Across 9,570 audited React sites, HTTP/2 (h2) is the default protocol on 24.1% of sites. HTTP/3 (h3) serves 68.2% (6,530 sites), and HTTP/1.1 still serves 7.7% (738 sites).
TTFB and the four LCP phases by HTML protocol
HTTP/3 wins its LCP lead in Time to First Byte. Median field TTFB drops from 1076 ms on HTTP/2 and 512 ms on HTTP/1.1 to 422 ms on HTTP/3. Over TCP, HTTP/2 needs a TCP handshake before TLS can finish. Over UDP, QUIC combines TCP and TLS setup into one round trip (or zero on a repeat visit).
HTML protocol paired with edge CDN
More than half of all HTTP/3 sites (69%) serve their main HTML through an edge CDN, compared with only 20% of HTTP/2 sites. Comparing protocol versions on the same delivery path separates QUIC from edge caching. On sites served straight from the origin server, HTTP/3 still cuts median TTFB from 1104 ms to 478 ms and reaches 87% on LCP (against 66% on HTTP/2). On Cloudflare, HTTP/3 cuts median TTFB to 462 ms and reaches 86%, against 1053 ms and 61% on Cloudflare HTTP/2. Fastly HTTP/3 reaches 398 ms TTFB and 96%.
| HTML protocol | Origin (no edge CDN) | Cloudflare | Fastly | CloudFront | Akamai |
|---|---|---|---|---|---|
| HTTP/3 (h3) | 87% 2,032 sites | 86% 579 sites | 96% 3,357 sites | 87% 532 sites | 73% 25 sites |
| HTTP/2 (h2) | 66% 1,853 sites | 61% 105 sites | 71% 86 sites | 62% 123 sites | 63% 66 sites |
| HTTP/1.1 | 83% 619 sites | 60% 34 sites | 96% 42 sites | 83% 34 sites | few sites |
HTML document protocol per platform
Wix serves the main HTML over HTTP/3 on 96% of its sites, and 94% of Wix sites have a good LCP. WordPress serves HTTP/2 on 70% of its sites, HTTP/3 on 24%, and HTTP/1.1 on 6%, and 63% of WordPress sites have a good LCP.
Wix 5,824 sitesHTTP/3 (h3) 96%94%
WordPress 2,342 sitesHTTP/2 (h2) 70%HTTP/3 (h3) 24%63%HTML protocol or the platform
Does the platform explain the HTTP/3 pass rate?
On WordPress, 66% of sites served over HTTP/3 have a good LCP, against 62% of WordPress sites on HTTP/2. Within WordPress, HTTP/3 and HTTP/2 sites have a good LCP about equally often.
Why HTTP/3 needs an HTTPS DNS record to help the first visit
A cold HTTP/2 connection takes two round trips before the browser can request the HTML: one for TCP and one for TLS. HTTP/3 runs over QUIC and finishes connection and TLS setup in one round trip. Even without an edge CDN, that cuts median origin TTFB from 1104 ms on HTTP/2 to 478 ms on HTTP/3. On a first visit, though, most servers only advertise HTTP/3 through the Alt-Svc response header. The browser only sees that header after the first HTML response has already arrived over HTTP/2. Publishing an HTTPS (type 65) DNS record with alpn="h3" tells the browser to use HTTP/3 on the very first request.
Understanding HTML document protocol
Turn on HTTP/3 at your CDN or web server and publish an HTTPS DNS record with alpn="h3" so cold visitors use QUIC on their very first document request. Across this dataset, 68.2% of sites serve their HTML over HTTP/3 and reach 91% good LCP (422 ms median TTFB), compared with 66% on HTTP/2 (1076 ms TTFB). Part of that 654 ms TTFB lead comes from edge CDNs, which terminate the connection close to the visitor. Even on direct origin servers without a CDN, HTTP/3 still trims 626 ms off median TTFB by removing a handshake round trip. If your HTML still runs over HTTP/1.1 (7.7% of sites), move to HTTP/2 or HTTP/3 first. Stylesheets, scripts, and the LCP image can then reuse the open document connection instead of opening six separate TCP connections.
By Arjen Karel · 9,570 crawled React sites (5,488 with phone Chrome field data, October 2026). How we measured.