Making TRAMP faster

Also, using persistent ssh connections makes a huge difference, esp. if you’ve got a heavy shell init on the local or remote side

  Host *
      ControlPath ~/.ssh/cm-%r@%h:%p
      ControlMaster auto
      ControlPersist 600

Isn't recent Tramp versions using this by default?

I thought TRAMP overrides that setting in your SSH config.

> TRAMP uses the ControlMaster=auto OpenSSH option by default, if possible. However, it overwrites ControlPath settings when initiating ssh sessions. TRAMP does this to fend off a stall if a master session opened outside the Emacs session is no longer open. That is why TRAMP prompts for the password again even if there is an ssh already open.

https://www.gnu.org/software/emacs/manual/html_node/tramp/Ss...

It does and it becomes a bit annoying if you were already persisting sessions, but you can just tell emacs to use the same sockets that ssh sets up.

It's a good optimization, but be careful with it since it's not 100% compatible with the normal behavior. A master connection (the first one you establish) will not be able to close until all other connections have done so. Not all software can handle this correctly.