The server you are ssh'ing/logon to, is trying to do a double reverse name lookup of your workstation IP address. This however fails and that is causing the delay.
Easiest way is to add the IP address and the name of your workstation to the "/etc/hosts" file of the server.
Real pro's configure a local nameserver
. Only the cowards set "UseDNS to "no" in the sshd.conf of the server
