HTML document protocol (HTTP/3 vs HTTP/2 vs HTTP/1.1) and the Core Web Vitals
HTTP/2, HTTP/3, or HTTP/1.1 on the main HTML document: how the protocol changes Time to First Byte (183 ms faster on HTTP/3) and how much comes from edge CDNs.
Three in five sites (61.7%) serve their main HTML document over HTTP/2, 23.7% use HTTP/3 over QUIC, and 14.6% still use HTTP/1.1. On HTTP/3, 86% of sites have a good LCP, against 81% on HTTP/2 and 83% on HTTP/1.1. In Chrome's field data, HTTP/3 cuts median Time to First Byte by 183 ms compared with HTTP/2 (533 ms against 716 ms).
LCP pass rate
Sites serving their HTML over HTTP/3 (h3) have a good LCP most often at 86%, followed by HTTP/1.1 at 83% and HTTP/2 (h2) at 81%. 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 206,244 audited sites, HTTP/2 (h2) is the default protocol on 61.7% of sites. HTTP/3 (h3) serves 23.7% (48,933 sites), and HTTP/1.1 still serves 14.6% (30,151 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 716 ms on HTTP/2 and 592 ms on HTTP/1.1 to 533 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 (56%) serve their main HTML through an edge CDN, compared with only 14% 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 727 ms to 663 ms and reaches 83% on LCP (against 81% on HTTP/2). On Cloudflare, HTTP/3 cuts median TTFB to 462 ms and reaches 89%, against 721 ms and 79% on Cloudflare HTTP/2. Fastly HTTP/3 reaches 424 ms TTFB and 91%.
| HTML protocol | Origin (no edge CDN) | Cloudflare | Fastly | CloudFront | Akamai |
|---|---|---|---|---|---|
| HTTP/3 (h3) | 83% 21,667 sites | 89% 19,171 sites | 91% 4,230 sites | 85% 2,594 sites | 87% 1,228 sites |
| HTTP/2 (h2) | 81% 109,376 sites | 79% 6,432 sites | 78% 2,356 sites | 79% 3,751 sites | 82% 3,726 sites |
| HTTP/1.1 | 84% 27,505 sites | 78% 1,184 sites | 78% 394 sites | 80% 572 sites | 81% 477 sites |
Understanding HTML document protocol
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 727 ms on HTTP/2 to 663 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.
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, 23.7% of sites serve their HTML over HTTP/3 and reach 86% good LCP (533 ms median TTFB), compared with 81% on HTTP/2 (716 ms TTFB). Part of that 183 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 64 ms off median TTFB by removing a handshake round trip. If your HTML still runs over HTTP/1.1 (14.6% 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.
How HTML document protocol plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,509 sites 20.8% of WordPress sites serve HTML over HTTP/3, passing LCP 6 points more often than those on HTTP/2.
Across WordPress origins, 20.8% serve main HTML over HTTP/3 (75% good LCP, 1.8s median), 71.9% use HTTP/2 (69% good LCP, 2.0s median), and 7.3% use HTTP/1.1.
Shopify 8,573 stores 95% of Shopify storefronts serve main HTML over HTTP/3.
Across Shopify storefronts, 95% serve main HTML over HTTP/3 (96% good LCP, 1.3s median), 0.8% use HTTP/2, and 4.2% use HTTP/1.1.
React & Next.js 9,570 sites 68.2% of React sites serve HTML over HTTP/3 (92% good LCP vs 65% on HTTP/2).
Across React sites, 68.2% serve main HTML over HTTP/3 (92% good LCP, 1.2s median) compared with 24.1% on HTTP/2 (65% good LCP, 2.1s median).
By Arjen Karel · 210,902 crawled sites (196,263 with all devices Chrome field data, 206,244 sites with HTML document protocol, October 2026). How we measured.