Why is my Red Hat Enterprise Linux server receiving very slow incoming ssh connections ?

Issue

• Why is the server performance is very slow especially with incoming SSH requests.
• When I do ssh -vvv to my server , it is taking a lot of time after
  "debug2: key: /root/.ssh/id_dsa (0x2b1b6429f110)" line and after "debug2: channel 0: send open
debug1: Entering interactive session."
• When I try to ssh to my server why am I getting a login prompt after some delay ?
• Why am I getting a slow ssh response ?
• Why is ssh or ftp take a long time to login into the server ?
• Why am I getting a password prompt after a delay of few seconds when I try to ssh into the server ?