There are other things you can do to increase performance, many have been covered in these forums.
Some examples:
-default aged threads to display set to a shorter interval (we're down to 2 weeks);
-extend your Who's Online time - we set ours to 30 mins;
-disable forum-wide searching;
-make sure my.cnf is optimized for your h/w;
-and there's other tips and tricks.
We run a 1.8ghz box w/ 1GB of RAM and see 150+ users online during our busy times, and usually always get subsecond response times.
