It seems to be that as soon as the number of connected users jumps up beyond a certain level the machine sags to its knees. Having said that, the CPU is always way, way too high.

Is there any official documentation which says amount of RAM per user connections? Or CPU power needed per connection? What I'm trying to establish is whether the below is a lot for a 3Gb dual CPU system or not:

10 runnable (green), 1370 sleeping (red), 15 dormant (blue) connections in activity monitor.

If it is down to poor store procs, ad-hoc queries, cursors and the like then fine, I'll keep digging.