HTML document compression on Wix sites

Sites with Brotli HTML compression have a good LCP most often: 92%, against 92% of all Wix sites.

97.9% of Wix sites use HTML compression, and 99% of those use Brotli.

Across the four LCP sub-parts in Chrome's field data, the largest gap between Brotli and no sits in resource load duration: 259 ms median for Brotli against 118 ms for no. Overall median field LCP is 1.2s for Brotli (TTFB 342 ms, load delay 481 ms, load duration 259 ms, render delay 137 ms) versus 1.2s for no.

React sets the HTML compression to Brotli on 97% of its sites, and 92% of React sites have a good LCP, against 92% of all sites.

FrameworkHTML compression on its sitesGood LCP

All Wix sites 5,621 sitesBrotli (br) 97%92%

React 5,620 sitesBrotli (br) 97%92%

Brotli (br) Uncompressed (none) Zstandard (zstd) Gzip

Does the framework explain the HTML compression difference?

Almost every site with Brotli HTML compression is a React site, and almost every React site has Brotli HTML compression, so the data can't tell Brotli HTML compression and React apart.

Why Brotli HTML compression speeds up resource discovery

Brotli uses a built-in dictionary of common HTML, CSS, and JavaScript tokens, shrinking HTML documents 15 to 20 percent more than Gzip at comparable CPU cost. Because the browser's preload scanner parses the HTML stream chunk by chunk as it arrives, a smaller compressed document delivers the <head> and hero <img> markup in fewer TCP or QUIC packets. Sites serving Brotli HTML record a 342 ms median TTFB and 1.2s median LCP, compared with 792 ms TTFB and 1.3s LCP on Gzip.