Host * ControlMaster auto ControlPath /tmp/%r@%h:%p
ControlMaster autowill use a master if one exists, or start a master otherwise.
ControlPathis the path to the control socket used for connection sharing.
%pare replaced with your username, host to which you are connecting and the port respectively. In addition, you may want to add
Ciphers arcfourin order to use the arcfour cipher which is faster than the default (aes128-cbc). The transfer rate of arcfour is about 90 MB/s, aes128-cbc is about 75 MB/s and the slowest is 3des-cbc, at 19 MB/s.