I had an interesting thing I hadn’t seen before on a VMware guest that was a Windows Server 2012 machine.

Symptoms:
System process (PID 4) 50% cpu or higher:  vmware 5.x + server 2012.

I looked at another 2012 server and noticed it had the e1000 NIC in it and I remember when building this current server I had changed it to the vmxnet3 thinking, oh…vmnet3 NIC must be better than the e1000.  I was wrong.  I don’t think Server 2012 likes the vmxnet3 for whatever reason (driver related) regardless of whether you have VMware Tools installed or not because I did; and it wasn’t having problems.  So I Changed the NIC from vmxnet3 to e1000.

Again; it’s related to a networking issue (References):

http://blogs.technet.com/b/yongrhee/archive/2009/08/07/how-to-troubleshoot-high-cpu-in-the-system-process.aspx
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1077
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2231

I don’t think any of those happen to actually say, switch from vmxnet3 to e1000 BUT that’s what I did and the problem went away!