I'm running on a dual-core Macbook Pro 2.5GHz with 4GB of RAM with Omnisphere installed on an external FW800 7200 rpm Hard Drive and Logic 8.0.2. I just record enabled 4 MIDI tracks with an Omnisphere multi and the CPU usage shot up to 100% with audio dropouts. I observe that only one CPU core is being utilized with the other being unused. My guess is that one instance of Omnisphere will load just one processor core and not use others.
I guess I need to change my work-flow to work within the constraints of my machine but I feel that Omnisphere being designed to work as a multi-instrument should perform satisfactorily with all 8 tracks enabled.
Any tips/tweaks on improving performance will be welcome. Thanks for all your contributions. I've learnt a lot from you guys. This forum rocks and Omnisphere is just Wow! Cant wait for the updates and new patches (...like I've really gone through all the ones I have already... yeah right!)
AFAIK it is normal behaviour that a plugin can only use a single core for every instance.
If you hit the ceiling with one instance you could try to move some parts of the first instance to a second one.
The operating system should assign the second instance to the 2nd core.
That approach works perfectly for me on my 8core mac.