Sometimes using Parallels, I found native osx applications 'stuttering' and hanging up for a few seconds, because the VM inside parallels is heavily abusing of cpu/ram/disk. Now, what I would love, is the ability to 'nice' the parallels VM processes, as to be able to give the VM very low priority, and therefore avoid to have the VM reduce the GUI and applications responsiveness. This could be implemented with a VM setting: "Priority" (Low, Standard, High). And then maybe an option for automatically lower the VM priority whenever VM window loses focus. This would allow to have a very responsive VM while we are using it, but avoid to have it 'freezes' the native applications while it's doing some background work.
