Did you download Samba 2.2.5 from this site:
http://www.amigasamba.org ? You may have noticed the comment next to the link for that file on the downloads page, it says the following: "Last 2.2.5 GCC based port. BETA!!".
That version is unoptimized and I think is still reliant on ixemul so its really only good for testing. This would explain the high resource requirements you are experiencing using it.
I remember messing around with that version a while back and had similar issues to you. I would suggest reverting to the latest stable release which is version 2.0.7, also available from that site and aminet.
