Speeding up SSH by Reusing Connections

From https://puppet.com/blog/speed-up-ssh-by-reusing-connections:

One way to enable this feature is to add the following to your ~/.ssh/config:

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

In a quick test with a particular host running ssh user@host whoami takes about 0.8s without that setting and takes about 0.1s with the setting above. Really speeds up bash-completion with scp.