Nope is the short answer.
You are assuming that applications run slower in virtualisation layers, but thankfully you are wrong. Yes, Plesk Windows isn't rapid I know but I have v8.3 on a dual 2.4GHz and v8.4 on a dual 2.6GHz (runing on VI) and they're extremely similar in terms of performance, not the same but almost identical. In fact my Virtual platform supports much faster writes due to the improved underlying hardware.
VMs are the only way to get full automatic redundancy and data-centres everywhere are spending millions porting the majority of their hosting products over.
Lea