Subresource CDN providers and the Core Web Vitals
Across audited sites, 99.3% (204,824) fetch requests from unfronted origin or custom hosts (82% good LCP), while 44.4% load assets via Cloudflare (81% good LCP), 25.3% via Amazon CloudFront (82% good LCP), and 18.8% via Fastly (85% good LCP, 1.5s median).
18.8% of sites use Fastly subresource CDN distribution, and 85% of those sites have a good LCP, against 82% of all sites.
LCP pass rate
Sites with Fastly subresource CDN distribution have a good LCP most often: 85%, against 82% of all sites. Sites with Netlify Edge subresource CDNs have it least often, at 74%.
Subresource CDN distribution usage
Origin/custom hosts is the most used: 99.3% of sites. Fastly is 18.8% of sites.
LCP phase breakdown by CDN serving page subresources
Across the four LCP sub-parts in Chrome's field data, the largest gap between Fastly and Netlify Edge sits in time to first byte (TTFB): 547 ms median for Fastly against 730 ms for Netlify Edge. Overall median field LCP is 1.5s for Fastly (TTFB 547 ms, load delay 397 ms, load duration 143 ms, render delay 234 ms) versus 1.9s for Netlify Edge.
Understanding subresource CDN providers
Which CDN edges actually serve the images, scripts, and fonts on a page
Even when a site's main HTML document is served directly from an origin server, its subresources (images, scripts, fonts, third-party libraries) frequently traverse global CDNs. Across all audited sites, 44.4% (91,586) load subresources from Cloudflare (81% good LCP, 1.6s median), 25.3% (52,129) from Amazon CloudFront (82% good LCP), 18.8% (38,747) from Fastly (85% good LCP, 1.5s median), and 4.6% (9,532) from Akamai (80% good LCP).
Serve static subresources (especially the LCP hero image, critical CSS, and web fonts) from the same edge CDN fronting your HTML document so requests coalesce over a single HTTP/2 or HTTP/3 connection. Across all audited sites, 44.4% fetch subresources from Cloudflare (81% good LCP) and 18.8% from Fastly (85% good LCP).
How subresource CDN distribution plays out per platform
What the field data shows when you isolate a single CMS or framework.
WordPress 65,509 sites 99.8% of WordPress sites fetch subresources from origin/custom hosts, 42.1% use Cloudflare, and 19.2% use CloudFront.
Across 65,509 WordPress sites, 99.8% serve subresources from origin or custom hosts (70% good LCP), 42.1% use Cloudflare (68% good LCP), 19.2% use CloudFront (66%), and 10.5% use Fastly (69%).
Shopify 8,573 stores 100.0% of Shopify stores serve assets from Cloudflare (96% good LCP) and 51.2% also load CloudFront assets.
Across 8,573 Shopify storefronts, 100.0% load subresources from Cloudflare (96% good LCP, 1.3s median), 51.2% load resources from Amazon CloudFront (94% good LCP), and 44.0% load resources from Fastly (94%).
React & Next.js 9,570 sites 74.5% of React & Next.js sites load subresources from CloudFront (90% good LCP) and 68.0% from Fastly (92%).
Across 9,570 React sites, 74.5% load subresources from Amazon CloudFront (90% good LCP, 1.3s median), 68.0% from Fastly (92% good LCP, 1.2s median), and 37.2% from Cloudflare (78% good LCP).
By Arjen Karel · 210,902 crawled sites (196,263 with all devices Chrome field data, 206,252 sites with subresource CDN distribution, October 2026). How we measured.