First of all thanks for you help and patience.
Regarding Multi Car Support - that’s right, I just forgot that. Now:
If everything is off the CPU load is 18%.
Playing the lower keyboard (Omnisphere, Diva): CPU load 55%
Playing the upper keyboard (Lush and UVI (with a sampled piano, no multilayer) with the effects: CPU load 61%, without the effect plugins 60%.
Playing both together (or just have the sustain pedal on one and play the other): CPU 100% and glitches.
Audio Buffer Size is 1024 samples, Sample rate is 44.1.
The same preset in MainStage shows the following:
If everything is off: 15% CPU load.
Playing the lower keyboard: 68% CPU load
Playing the upper keyboard: 59% CPU load
Playing them together: max. CPU load is between 80 and 85%.
Sample rate is the same, the buffer size is 256 plus safety means 512 in total. In GP I have 1042.
Based on Gigperformers comparison chart the CPU load should be drastically lower in GP. They say 4 instances of Omnisphere makes a CPU load of 60% in Mainstage and only 20% in Gigperformer. Why than in may case it is opposite? I understand that Diva eats a lot of CPU, but all the other plugins in my rackspace? They are more then moderate.