Shopify subresource compression algorithms and the Core Web Vitals

Sites with Dictionary-Compressed Brotli (dcb) subresource HTTP compression have a good LCP most often: 97%, against 97% of all Shopify sites. Sites with Zstandard (zstd) compression subresource compression have it least often, at 96%.

Unencoded binary assets is the most used: 100.0% of Shopify sites. Dictionary-Compressed Brotli (dcb) is 95.5% of Shopify sites.

Across the four LCP sub-parts in Chrome's field data, the largest gap between Dictionary-Compressed Brotli (dcb) and Zstandard (zstd) compression sits in resource load delay: 625 ms median for Dictionary-Compressed Brotli (dcb) against 656 ms for Zstandard (zstd) compression. Overall median field LCP is 1.3s for Dictionary-Compressed Brotli (dcb) (TTFB 303 ms, load delay 625 ms, load duration 153 ms, render delay 306 ms) versus 1.3s for Zstandard (zstd) compression.

Vue sets the subresource HTTP compression to Dictionary-Compressed Brotli (dcb) on 97% of its sites, and 97% of Vue sites have a good LCP, against 97% of all sites. jQuery sets the subresource HTTP compression to unencoded binary assets on 100% of its sites, and 95% of jQuery sites have a good LCP.

FrameworkSubresource HTTP compression on its sitesGood LCP

All Shopify sites 8,246 sitesUnencoded binary assets (images / WOFF2) 100%Brotli (Content-Encoding: br) 100%Gzip (Content-Encoding: gzip) 100%Dictionary-Compressed Brotli (dcb) 96%Zstandard (Content-Encoding: zstd) 69%97%

Vue 933 sitesUnencoded binary assets (images / WOFF2) 100%Gzip (Content-Encoding: gzip) 100%Brotli (Content-Encoding: br) 100%Dictionary-Compressed Brotli (dcb) 97%Zstandard (Content-Encoding: zstd) 76%97%

jQuery 3,153 sitesUnencoded binary assets (images / WOFF2) 100%Gzip (Content-Encoding: gzip) 100%Brotli (Content-Encoding: br) 100%Dictionary-Compressed Brotli (dcb) 94%Zstandard (Content-Encoding: zstd) 78%95%

Unencoded binary assets (images / WOFF2) Brotli (Content-Encoding: br) Gzip (Content-Encoding: gzip) Dictionary-Compressed Brotli (dcb) Zstandard (Content-Encoding: zstd)

Does the framework explain the subresource HTTP compression difference?

On jQuery, 96% of sites with Dictionary-Compressed Brotli (dcb) subresource HTTP compression have a good LCP, against 95% of jQuery sites with unencoded binary assets. Within jQuery, sites with Dictionary-Compressed Brotli (dcb) and unencoded binary assets have a good LCP about equally often. On Vue, 97% of sites with Dictionary-Compressed Brotli (dcb) subresource HTTP compression have a good LCP, against 97% of Vue sites with unencoded binary assets. Within Vue, sites with Dictionary-Compressed Brotli (dcb) and unencoded binary assets have a good LCP about equally often.

Brotli, Zstandard (zstd), and Dictionary-Compressed Brotli (dcb) across page subresources

Nearly every page (100.0%) transfers pre-compressed binary formats like WebP, AVIF, and WOFF2 without extra Content-Encoding. For text subresources (JS, CSS, SVG, JSON), 99.7% of sites use Gzip (97% good LCP, 1.3s median), 99.9% use Brotli (97% good LCP), 68.7% include Zstandard responses (96% good LCP, often from Meta/Google third-party scripts), and 95.5% (7,879 sites, led by Shopify/Cloudflare) use shared-dictionary Brotli (dcb) to achieve 97% good LCP (1.3s median).