I use a special trick because he’s often ssh’ing all over the place. Add in your
Host * ControlMaster auto ControlPath /tmp/%r@%h:%p
It will save your first connection to a host as a socket in
/tmp and then all subsequent ssh connections to the same host are open instantly because there is no key renegotiation on the way. The side effect is that the child-connections cannot be closed until the first one closes, but I find it convenient because it tells me that I still have a console open on the server that I should close.