Some people (including me) may find that when logging in to proftpd, there is a short pause at the start of the connection.
I use flashfxp and dreamweaver for transferring files via ftp and this small pause can be quite annoying when making small fast changes to files whilst developing sites.
The pause occurs when proftpd is trying to identify the remote username.
In the conf file, IdentLookups may be set to off but this is not for all users.
In the <Global></Global> section add the line:
Don't forget to restart proftpd with:
service proftpd restart
Be aware that the only thing that will change is that the "AuthenticatedUserID" column in the xferlog will be empty.