New
#11
VMs don't work the way some folks think. You're not "dedicating" cores to a VM; you're simply saying that the VM instructions will be allowed a thread path to the host machine cores. The host processor doesn't care what instructions it's executing or where they're coming from since they're all coming through the same pipes. It's no different than running a bunch of programs at once on the host alone. If you have the power like most 8-core (thread) processors do today, I doubt you'd see any difference in drag. You'd be surprised at just how little the cores are used for most apps.
I ran all eight cores when I had the Windows 8 preview loaded on Oracle VM. I even gave it a 100% cap and had no problems switching back and forth to the host. And I'm just running a "old" i7-2600. What really bogs a system down is I/O. Plant the VM disk on a SSD and it will rip!