HTML document CDN delivery and the Core Web Vitals
Direct from origin versus Cloudflare, Fastly, CloudFront, or Akamai: how serving the main HTML document through an edge CDN changes Time to First Byte (492 ms on Cloudflare vs 600 ms from origin) and Largest Contentful Paint.
Three in four sites, 76.9%, have no an HTML edge CDN. Of the 23.1% that do, 2% use Vercel as, and 89% of those sites have a good LCP, against 86% of all sites.
LCP pass rate
Sites with Vercel as an HTML edge CDN have a good LCP most often: 89%, against 86% of all sites. Sites with Netlify as CDN have it least often, at 78%.
An HTML edge CDN usage
One in four sites uses an HTML edge CDN, and 56% of those use Cloudflare as. Vercel as is 2% of the sites with CDN, 0.6% of all sites.
Where an HTML CDN saves time: TTFB and the four LCP phases
Across the four LCP sub-parts in Chrome's field data, the largest gap between Vercel as and no sits in time to first byte (TTFB): 238 ms median for Vercel as against 600 ms for no. Overall median field LCP is 1.4s for Vercel as (TTFB 238 ms, load delay 595 ms, load duration 130 ms, render delay 208 ms) versus 1.4s for no.
Understanding HTML document CDN delivery
Why putting the HTML document on an edge CDN cuts TTFB
Static assets like images and scripts are easy to put on a CDN, but the browser cannot discover any of them until the main HTML document arrives. Routing the main domain through an edge network terminates DNS, TCP, and TLS at a point of presence near the visitor, and full-page HTML caching at the edge removes the origin server round trip entirely. In Chrome's field data, serving HTML through Cloudflare cuts median TTFB to 492 ms and Fastly cuts it to 550 ms, compared with 600 ms for documents served directly from the origin.
Serve the main HTML document through an edge CDN and cache anonymous page views at the edge wherever possible. Across the dataset, 76.9% of sites still serve HTML directly from an origin server (86% good LCP, 600 ms median TTFB), while sites on Cloudflare (88% good LCP, 492 ms TTFB) and Fastly (87% good LCP, 550 ms TTFB) start rendering significantly earlier. Even when HTML cannot be cached publicly, edge TLS termination, HTTP/3 support, and tiered origin routing cut connection latency on every navigation.
How an HTML edge CDN plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,509 sites 86.1% of WordPress sites serve main HTML directly from the origin server without a detected CDN proxy.
Across WordPress sites, 86.1% serve main HTML directly from the origin server (76% good LCP, 1.7s median) and 8.4% proxy main HTML through Cloudflare (76% good LCP).
React & Next.js 9,570 sites React sites serving HTML from Fastly (36.4%) pass LCP at 91% vs 73% on direct origins.
Across React sites, 36.4% serve main HTML from Fastly edge nodes (91% good LCP, 1.2s median) compared with 47.1% serving HTML from direct origins (73% good LCP, 1.7s median, 18 points apart).
By Arjen Karel · 210,902 crawled sites (69,745 with desktop Chrome field data, 206,244 sites with an HTML edge CDN, October 2026). How we measured.