After installing Oracle Linux on Virtualbox, I noticed that login in was quite slow. Between the time we enter the login and the moment it asks the password it takes a few seconds.
The solution was to disable the usage of reverse IP resolution on the ssh server.
It can be done by adding/changing the following line on /etc/ssh/sshd_config
UseDNS no
And restart the ssh deamon:
# service sshd restart Stopping sshd: [ OK ] Starting sshd: [ OK ]