Yes, but storing "supports HTTP2" for a given server for a given time after connecting to that server and negotiating the upgrade would also do the job. One of

Yes, but storing "supports HTTP2" for a given server for a given time after connecting to that server and negotiating the upgrade would also do the job. One of the problems with HTTP 1.x is that it is stateless - every time you want something from a server, you treat it as if it is the first time you talk to it. I understand this is by design, but as a consequence we are transmitting all the same headers to the server all the time... which can be mitigated with HTTP2, except that we still need to do that (send all headers) and the HTTP2 upgrade, every time we open a new TCP socket to that server.