I'm not sure I understand what you're asking, but if you want a single number for Hyper-V's "overhead", that information isn't avaialble. All virtualization platform will generate some overhead related to coordinating virtual partitions/environments. The overhead will vary based on usage patterns and activities that are occuring on the system. The best approach is to implement performance testing as part of a deployment plan. The better you understand your workloads, the better performance you'll achieve on production systems. I hope this is somewhat helpful.