[csswizardry]

You are correct that this is an optimisation only available to H2+, but optimising to the H/1.x use-case is a use-case not worth optimising for—if one cared about web performance that much, they wouldn’t be running H1/.x in the first place.

Most connections on the web nowadays are over H2+: https://almanac.httparchive.org/en/2024/http#http-version-ad...

[giantrobot]

> if one cared about web performance that much, they wouldn’t be running H1/.x in the first place.

You may not have intended it this way but this statement very much reads as "just use Chrome". There's lots of microbrowsers in the world generating link previews, users stuck with proxies, web spiders, and people stuck with old browsers that don't necessarily have H2 connectivity.

That doesn't mean over-optimize for HTTP 1.x but decent performance in that case should not be ignored. If you can make HTTP 1.x performant then H2 connections will be as well by default.

Far too many pages download gobs of unnecessary resources just because they didn't bother tree shaking and minifying resources. Huge populations of web users at any given moment are stuck on 2G and 3G equivalent connections. Depending where I am in town my 5G phone can barely manage to load the typical news website because of poor signal quality.