I just discovered (not new) feature of OpenSSH, which allows to have several sessions over a single network connection. If you are once connected to the server, all other sessions can use existing connections and this makes much faster things like working with remote SVN or shell completion of remote filenames.
All you need in config file to make it work is something like this:
Host *
ControlPath ~/.ssh/sock/%r@%h:%p
ControlMaster auto
