Performance issues on virtual 2K12 server

Client moved from old virtual 2K3 server to newer 2K12 server. They use an IT vendor to manage all of their IT setup. They connect via Terminal Services if I understand correctly. Apparently this legacy VFP application is run from the server by all users. Performance is inconsistent, with many times it getting almost frozen for some unknown reason. Other times it's fine. No good rhyme/reason standing out. A/V and other scans have the VFP app and data folders excluded (or so I'm told). For those who have worked with VFP apps in TS mode, any tips?

tia, --Mike