List users of each level

Hi

I'm trying to list all users on a certain membership level.
I know that I can use $member->on_level() on certain user to get the level. This means that one way to get all users at a certain level would be to loop all users and get the level for each user. This seems to be highly ineffective though if I have lots of users.

Is there any method or sql query that I can use to only get users of certain level of membership?

Thanks!

BR
Tobias Dahlberg