Today, I got through half of a project and had to quit. It's really frustrating. The CPU kept pegging the red, I'd get error messages, and one time the whole computer locked up, forcing me to reboot.
I had about 15 or 16 instances of Kontakt 3, mostly using VSL samples that came with Kontakt, as well as East West's Symphonic Orchestra Gold. It's sort of the usual set-up that a lot of composers use: A track with tremolo violins, a track with arco violins, a track with marcato violins, a track with tremolo celli, a track with staccato celli, etc., etc., etc. All the while, I automated the mod wheel to take advantage of volume and intensity changes as the tracks played.
Anyway... I didn't even get to the woodwind section, nor the harp, or percussion. My iMac kept freaking out with just the piano, brass and strings.
Also, I don't know if this is normal or not, but as I watched the CPU bar in the "Audio Performance" window, I noticed that it was never constant, but would frequently spike. Is this normal?
What do you think? Are 15 instances of Kontakt 3 just too much for a 2 GHz Intel Core Duo iMac with 2 GB of RAM? Or is something else wrong with my set-up or my computer? Do I need to defragment a hard drive or something?
I have my samples stored on an external Firewire drive (since iMacs can have only one internal drive), so my sounds aren't taxing the main hard drive. But maybe they're taxing the CPU in another way?
I was hoping to limp along with my iMac for another year and save up to buy a Mac Pro with those 8 processors, a Gazillion Gigs of RAM, and a couple extra Terabyte hard drives!

Your advice would be appreciated. Thanks!
Kevin