If you are using VMWare or Hyper-V, particularly Hyper-V, as your hypervisor you may wish to try turning off dynamic memory (if you haven't already). It's a neat technology but can potentially cause hitches in the guest OS when it changes the RAM amount. Not noticeable for most kinds of services but might cause issues with something that is realtime like a game. Also make sure you haven't oversubscried the physical RAM, while it'll let you do that the penalty for paging is even more than normal.