CPU is almost never the bottle neck with OH. When it is it is usually because of poorly written rules.
If the Android app is slower, it is probably most likely to be caused by network, not CPU. I can really see this being a problem when switching to a VM as now you have another layer of networking to pass through.
On memory constrained machines (512 mb or less) ram can become a problem for larger oh instances but 1 gb and above should be fine.
So no, I wouldn’t expect to see a significant speed up in a move from a RPi 3 to a VM. OH isn’t CPU constrained enough. Most of the time oh is waiting around for events to happen or waiting for io.