WordPress subresource CDN providers and the Core Web Vitals

Sites with origin/custom hosts subresource CDN distribution have a good LCP most often: 70%, against 70% of all WordPress sites. Sites with Vercel Edge subresource CDNs have it least often, at 63%.

Origin/custom hosts is the most used: 99.8% of WordPress sites.

Across the four LCP sub-parts in Chrome's field data, the largest gap between origin/custom hosts and Vercel Edge sits in time to first byte (TTFB): 1117 ms median for origin/custom hosts against 1174 ms for Vercel Edge. Overall median field LCP is 2.0s for origin/custom hosts (TTFB 1117 ms, load delay 355 ms, load duration 181 ms, render delay 242 ms) versus 2.3s for Vercel Edge.

Vue sets the subresource CDN distribution to origin/custom hosts on 100% of its sites, and 67% of Vue sites have a good LCP, against 70% of all sites.

FrameworkSubresource CDN distribution on its sitesGood LCP

All WordPress sites 63,295 sitesDirect origin / custom host 100%Cloudflare CDN 42%Amazon CloudFront 19%Fastly CDN 11%70%

Alpine 380 sitesDirect origin / custom host 99%Cloudflare CDN 72%Amazon CloudFront 36%Fastly CDN 22%Akamai CDN 12%78%

jQuery 60,314 sitesDirect origin / custom host 100%Cloudflare CDN 43%Amazon CloudFront 20%Fastly CDN 11%69%

Vue 4,844 sitesDirect origin / custom host 100%Cloudflare CDN 36%Amazon CloudFront 17%67%

React 2,233 sitesDirect origin / custom host 100%Cloudflare CDN 52%Amazon CloudFront 27%Fastly CDN 15%63%

Direct origin / custom host Cloudflare CDN Amazon CloudFront Fastly CDN Akamai CDN Vercel Edge Network Netlify Edge

Does the framework explain the subresource CDN distribution difference?

Almost every site with origin/custom hosts subresource CDN distribution is a jQuery site, and almost every jQuery site has origin/custom hosts subresource CDN distribution, so the data can't tell origin/custom hosts subresource CDN distribution and jQuery apart. On Vue, 67% of sites with origin/custom hosts subresource CDN distribution have a good LCP, against 66% of Vue sites with Cloudflare. Within Vue, sites with origin/custom hosts and Cloudflare have a good LCP about equally often. On React, 63% of sites with origin/custom hosts subresource CDN distribution have a good LCP, against 59% of React sites with Cloudflare. Within React, sites with origin/custom hosts and Cloudflare have a good LCP about equally often.

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, 42.1% (26,661) load subresources from Cloudflare (67% good LCP, 2.0s median), 19.2% (12,135) from Amazon CloudFront (65% good LCP), 10.5% (6,672) from Fastly (68% good LCP, 2.0s median), and 4.2% (2,637) from Akamai (66% good LCP).