I would bet this has nothing to do with Samba itself. Sounds like you may have IPv6 running on the server. That can cause very slow network response in some networks, depending what else is in the network. To see if IPv6 is running, open a konsole on your server, su to root, and run lsmod and look to see if IPv6 is there. If it is, disable it, and try again.
It would also help for you to include more information on your next post. Post distro, version, any version information for the suspected problem program etc.
If this is a samba problem, post the smb.conf file. Can't tell squat without that.