Hi, performance wise, is it better to have all users connect using a single user account (multiple sessions), or create multiple user accounts?

For strict performance, very little difference I believe. But you should definately give each individual user their own user account, for no other reason than security and data consistency (otherwise you'll get many users that have full access to each others documents). You can (and probably should) make all users members of the same group if you wish, but you definately want each to have their own account. I can think of no good reason what so ever, that many users should share one account, other than perhaps laziness of the administrator not wanting to spend the time to set the server up correctly (I am not pointing fingers at anybody with this comment, it simply is a statement). Besides, if you have multiple users accessing the same user account, and something goes wrong with the server, how are you going to know who to talk to about it?

Lightning, agreed! Also, you certainly wouldn't want to use profiles with one account either! I did that here in the school I work in (we have one account for internet access) I very quickly ended up with a 320MB profile, it takes a long time to load!!