I just installed two new virtual machines with Windows 8 and Windows 8.1 on our VMWare ESXi 5.1 Server and noticed a base load of about 800 Mhz without the machine doing actual work.
Now I wonder how one can reduce this to a minimum (e.g. my Linux fileserver has a minimum load of 6-10 Mhz, and Windows 2003 one of 40 Mhz). Believing Microsoft designed this OS to also run on mobile devices, there must be switches that stop the system from doing useless stuff. Any ideas?
In addition to Mark Henderson's comment you may also want to check out the Optimization Guide for Windows 7 and Windows 8 Virtual Desktops in Horizon with View @ VMware.com and follow most of those optimizations which may cut down on CPU usage, and will for sure cut down on disks I/O because desktop OSes are far more I/O intensive if left unchanged than server OSes. It doesn't matter if the guide says it's for View, most all of the changes in Windows apply even if you run it on ESXi without View.
Windows 8/8.1 does not have such a high constant base load, neither on physical nor on virtual machines.
I have seen similar issues caused by software installations that corrupt the WMI stack (Unfortunately this is very hard to diagnose and fix), or maybe it is just caused by Antivirus software.
Check what processes and/or services are causing the CPU load, and start trouble shooting with this information. As always "Google is your friend"!
There's a fling that might help you: VMware OS Optimization Tool
As Reality Extractor points out these optimizations apply even if you run it on ESXi without View.