When you connect to your server via FTP, the Identd server tries to identify the machine you are connecting with, in order to record the details in the server logs, but because you are behind a firewall it can't directly reach your machine - hence the delay. To remove these checks you can do the following:
1) Connect to your server via SSH and login as admin, then 'su -' to root. At the prompt, type:
cp /etc/proftpd/proftpd.conf.wp proftpd.conf.wp.bak
2) At the top of the file insert the following lines:
3) Press [CTRL-X], Y then [RETURN] to save the file and exit the editor. Finally type:
Now, when you access your server via FTP from behind a firewall, you will notice that it responds to your requests much quicker.
If you have any questions (or need further help), please post them as comments below.