Windows Server Core and high CPU usage in Task Manager

I noticed that when I'm running Windows Server 2008 Core on a Virtual PC virtual machine and Task Manager (by pressing Ctrl+Shift+Esc or Ctrl+Alt+Del and then selecting Task Manager). Normally, Task Manager uses about (less than) 5% of CPU, but in Server Core the utilization doesn't drop below 25%, and can be about 60%.

I'm yet to verify whether this is a problem with my virtual machine setup, but it seems strange that Task Manager would need so much CPU time in a virtual machine, since a virtual machine with identical settings running Task Manager on normal Windows GUI uses much less CPU time.