virtualbox high cpu

[eric-yrHdaQSNc4gdnm+yROfE0A at public.gmane.org (Eric Chadbourne)]

hi all.

anybody running redhat / fedora as a guest on xp and experiencing very 
high usage of the cpu?  if yes how did you fix it?  in the docs i see a 
suggestion about recompiling the guest kernel and to select a timer 
frequency of 100Hz.  here's an example of virtualbox using 50% of the 
cpu while centos isn't really doing anything. 
http://newmag.files.wordpress.com/2009/05/vbox_pig.png

thanks for any tips,
eric c.