> HTTP/2 can only bring advantages if you actually go all the way to push/bundle resources into responses
Compared to well-optimized HTTP/1 (e.g. using minified CSS and sprite-sheets), sure. Compared to most HTTP/1 deployments, though: no. HTTP/2 gives you tons of advantages "for free" that you need build-time processes to attain in HTTP/1. With HTTP/2, you can do "the naive thing" that'd you'd have done on the 1995 Web in Notepad, and it'll be the optimal thing.
Also, HTTP/2 means less OS packet-switching overhead server-side if you have ancillary connections (e.g. websockets) open against the host, since those also get muxed into the same carrier socket.
Also, mobile clients wake up less, because there's only one TCP socket to do idle-keepalive on.
HTTP/2 also means that TCP's Nagling has more to work with, and so is less likely to end up needing to waste bandwidth on emitting many undersized packets—it can just pack N short requests into the same TCP jumbo frame, since they're all going to the same place.
I would also point out an indirect "advantage": HTTP/2 makes it cheaper to serve ads proxied through the first-party host (as HTTP/2 flows) than for the client to hit the third-party ad servers directly. People can still block the ads/trackers either way, but served inline to the origin like this, the people who don't block ads, will get a better experience.
Compared to well-optimized HTTP/1 (e.g. using minified CSS and sprite-sheets), sure. Compared to most HTTP/1 deployments, though: no. HTTP/2 gives you tons of advantages "for free" that you need build-time processes to attain in HTTP/1. With HTTP/2, you can do "the naive thing" that'd you'd have done on the 1995 Web in Notepad, and it'll be the optimal thing.
Also, HTTP/2 means less OS packet-switching overhead server-side if you have ancillary connections (e.g. websockets) open against the host, since those also get muxed into the same carrier socket.
Also, mobile clients wake up less, because there's only one TCP socket to do idle-keepalive on.
HTTP/2 also means that TCP's Nagling has more to work with, and so is less likely to end up needing to waste bandwidth on emitting many undersized packets—it can just pack N short requests into the same TCP jumbo frame, since they're all going to the same place.
I would also point out an indirect "advantage": HTTP/2 makes it cheaper to serve ads proxied through the first-party host (as HTTP/2 flows) than for the client to hit the third-party ad servers directly. People can still block the ads/trackers either way, but served inline to the origin like this, the people who don't block ads, will get a better experience.