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 (111 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, 88% of sites have a good LCP, against 86% on HTTP/2 and 85% on HTTP/1.1. In Chrome's field data, HTTP/3 cuts median Time to First Byte by 111 ms compared with HTTP/2 (505 ms against 616 ms).
LCP pass rate
Sites serving their HTML over HTTP/3 (h3) have a good LCP most often at 88%, followed by HTTP/2 (h2) at 86% and HTTP/1.1 at 85%.
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 616 ms on HTTP/2 and 524 ms on HTTP/1.1 to 505 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 626 ms to 599 ms and reaches 85% on LCP (against 86% on HTTP/2). On Cloudflare, HTTP/3 cuts median TTFB to 438 ms and reaches 90%, against 656 ms and 85% on Cloudflare HTTP/2. Fastly HTTP/3 reaches 411 ms TTFB and 88%.
| HTML protocol | Origin (no edge CDN) | Cloudflare | Fastly | CloudFront | Akamai |
|---|---|---|---|---|---|
| HTTP/3 (h3) | 85% 21,667 sites | 90% 19,171 sites | 88% 4,230 sites | 87% 2,594 sites | 91% 1,228 sites |
| HTTP/2 (h2) | 86% 109,376 sites | 85% 6,432 sites | 86% 2,356 sites | 82% 3,751 sites | 88% 3,726 sites |
| HTTP/1.1 | 85% 27,505 sites | 82% 1,184 sites | 86% 394 sites | 83% 572 sites | 84% 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 626 ms on HTTP/2 to 599 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 88% good LCP (505 ms median TTFB), compared with 86% on HTTP/2 (616 ms TTFB). Part of that 111 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 27 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.
Shopify 8,573 stores 95% of Shopify storefronts serve main HTML over HTTP/3.
Across Shopify storefronts, 95% serve main HTML over HTTP/3 (97% 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 (86% good LCP vs 69% on HTTP/2).
Across React sites, 68.2% serve main HTML over HTTP/3 (86% good LCP, 1.3s median) compared with 24.1% on HTTP/2 (69% good LCP, 1.9s median).
By Arjen Karel · 210,902 crawled sites (69,745 with desktop Chrome field data, 206,244 sites with HTML document protocol, October 2026). How we measured.