I am running Windows 7 x64 both as a host and a guest VM using VMWare Workstation v9. Here are the figures of Windows Experience Index for each instance, so you can estimate virtualization efficiency: Host Windows 7: Guest Windows 7 - VMWare Workstation v.9: Guest VM is allocated 2 cores, out of 4 cores total on my Intel i7-4770. As you probably have heard, Windows 7 uses logarithmic scale for its performance score.