VMware have recently reported an issue with RSS (Receive Side Scaling) not functioning correctly on virtual machines running VMware Tools 9.10.0 up to 10.1.5. This affects Windows Server 2012 onwards and will result in reduced performance. At the moment the recommended fix is downgrade VMware tools to 9.4.15. The full article can be read here
If you are using the vmxnet3 driver RSS is disabled by default. You can check the status of RSS by going into the properties of the network adapter inside the guest, and clicking the advanced tab.