This sounds exactly like the issue described in this thread:
vmxnet3 adapter on windows server 2012 with MSSQL server bottleneck problem
Are you also using the vmxnet3 vNIC?
If yes try one of these workarounds mentioned in the other thread (I would go with LRO for starters, also don't forget to reboot):
Use E1000E instead of vmxnext3
Use jumbo frames (not really good for us but may be a good option for others...)
Disable LRO on a VMXNET3 : Enable or Disable LRO on a VMXNET3 Adapter on a Windows Virtual Machine