The State of Web Vitals

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 (653 ms faster on HTTP/3) and how much comes from edge CDNs.

Field data PhoneDesktopAll Scope All sites October 2026 edition · All devices field outcomes · React sites only
React Scoped to 9,570 sites out of 210,902 analyzed (frameworks) Compare with all sites →

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, 92% of React sites have a good LCP, against 65% on HTTP/2 and 84% on HTTP/1.1. In Chrome's field data, HTTP/3 cuts median Time to First Byte by 653 ms compared with HTTP/2 (436 ms against 1089 ms).

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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LCP pass rate

Sites serving their HTML over HTTP/3 (h3) have a good LCP most often at 92%, followed by HTTP/1.1 at 84% and HTTP/2 (h2) at 65%. 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.

SitesGood, needs improvement, poor LCPMedian
All React sites9,11085%1.4s
HTTP/3 (h3) 68.2%6,18992%1.2s
HTTP/1.1 7.7%70584%1.3s
HTTP/2 (h2) 24.1%2,21665%2.1s
GoodNeeds improvementPoorSites: with Chrome field data
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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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).

HTTP/3 (h3) 68.2% HTTP/2 (h2) 24.1%
HTTP/3 (h3) 68.2% HTTP/2 (h2) 24.1% HTTP/1.1 7.7%
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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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 1089 ms on HTTP/2 and 483 ms on HTTP/1.1 to 436 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).

Median LCP phase breakdown (Chrome field p75) Median TTFB Median LCP
All React sites 6,740516 ms439 ms516 ms1.4s
HTTP/3 (h3) 4,566436 ms454 ms436 ms1.2s
HTTP/1.1 538483 ms354 ms483 ms1.3s
HTTP/2 (h2) 1,6361089 ms380 ms261 ms1089 ms2.1s
TTFB Resource load delay Resource load time Element render delay
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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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 1122 ms to 507 ms and reaches 87% on LCP (against 65% on HTTP/2). On Cloudflare, HTTP/3 cuts median TTFB to 453 ms and reaches 87%, against 1246 ms and 55% on Cloudflare HTTP/2. Fastly HTTP/3 reaches 404 ms TTFB and 96%.

HTML protocol Origin (no edge CDN) Cloudflare Fastly CloudFront Akamai
HTTP/3 (h3)
87% 507 ms TTFB 2,032 sites
87% 453 ms TTFB 579 sites
96% 404 ms TTFB 3,357 sites
87% 453 ms TTFB 532 sites
84% 430 ms TTFB 25 sites
HTTP/2 (h2)
65% 1122 ms TTFB 1,853 sites
55% 1246 ms TTFB 105 sites
65% 814 ms TTFB 86 sites
69% 832 ms TTFB 123 sites
66% 1030 ms TTFB 66 sites
HTTP/1.1
84% 490 ms TTFB 619 sites
76% 378 ms TTFB 34 sites
90% 439 ms TTFB 42 sites
76% 553 ms TTFB 34 sites
few sites
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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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 61% of WordPress sites have a good LCP.

PlatformHTML document protocol on its sitesGood LCP
All React sites 9,570 sitesHTTP/3 (h3) 68%HTTP/2 (h2) 24%85%
Wix 5,824 sitesHTTP/3 (h3) 96%94%
WordPress 2,342 sitesHTTP/2 (h2) 70%HTTP/3 (h3) 24%61%
HTTP/3 (h3) HTTP/2 (h2) HTTP/1.1
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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HTML protocol or the platform

Does the platform explain the HTTP/3 pass rate?

On WordPress, 65% of sites served over HTTP/3 have a good LCP, against 60% 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 1122 ms on HTTP/2 to 507 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.

The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
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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 92% good LCP (436 ms median TTFB), compared with 65% on HTTP/2 (1089 ms TTFB). Part of that 653 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 615 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.

Go fix it TTFB: connection duration → Configure Cloudflare for passing the Core Web Vitals →
The State of Web Vitals · October 2026 · React: 9,570 crawled sites · 9,110 with all devices field dataBy Arjen Karel · corewebvitals.io/state-of-cwv
Related signals Uncompressed text responses → HTML size (kB) → Connection hints → ETag present → By Arjen Karel · 9,570 crawled React sites (9,110 with all devices Chrome field data, October 2026) · How we measured