I have made sure all the VMs have at least 20 gig of free vHDD space to eliminate any issue with drive space. We also have used a Fluke MicroScanner to check out our physical cables and found a couple of suspect cables that we replaced as well.
Here are some test results, SMB file copy from a 2008R2 VM that has NIC offloading turned on to the new 2012R2 box with no PV tools so its using the base Windows Realtek driver and got 24 Mbps. Not great but much better than the 64-72 Kbps I get between two 2008R2 boxes with offloading turned on. Same test from 2008R2 VM with NIC offloading turned off and I get the same 24 Mbps. All of these VMs are on the same host.
Ok installed the PV tools on the 2012R2 server. Copy from a 2008R2 VM with NIC Offloading ON and the 350 meg file copied in a flash. Resource Monitor showed 2 Gbps. Copy from the VM with NIC Offloading OFF and the copied at 225 Mbps.
Maybe I should just start do inplace upgrades on my servers!!!!