Guess the problem? VFP9, HyperV, 2012R2

A former client from way back when emailed me with a brief question on

"running VFP 9 on a server with HyperV and Windows Server 2012R2." They are migrating an existing app from Server 2003 and he says on the new machine, "it runs like a dog" and I'm guessing he doesn't mean greyhound.

With this lack of clues, has anyone got a shot-in-the-dark guess what might be going wrong?