I've recently added a few things to my 3 yr old G4. A new stick of RAM, for a total of 1.25GB, Logic 7 upgrade, and also a Delta 44 Soundcard. Lately the performance of my computer is really bad. I can't even have more than 2 audio/instrument tracks playing in Logic without the audio turning really crappy (distortion, low fidelity). The CPU meters in both Logic and Apple's Activity monitor sky rocket fast when I press play in logic. The processing really backs up. Is there anything I can do make my computer perform faster? I have a G4 933Mhz with a 133Mhz front side bus so I thought I had enough power. Please help

have you tried Utilities>Disk Utility>Verify/Repair Permissions?
I get that problem when I try to set my latency too low. or when I run background apps like virus protection or airport.