I have installed Forefront TMG server in a virtual machine in VMware Workstation 9.0.1, the question is when it takes a while as I was working half day starts slow virtual machine. The machine has 10gb of ram and work with 10 users at most. The only solution I have now is 500mb apply whenever saturates and starts working again perfect, but not sure if vmware failure or Forefront, Forefront don't have excessive flood, normal multicasts and some other small things.
I have 2 Internal, one with dns and other without, two external interfaces for redundancy without dns too. The persistent rules are good and the same for Nat routes. The Dns are internal too, and all responses good.