VMware Fusion 5 with Windows 8 64 bit on MacBook Air Constant High CPU usage
Check the support forums on the Apple site.  I have had the same problem with 2 MacBook Airs and a new MacBook Pro Retina.  The issue is due to excessive disk writes the OSx is pushing to create the Hibernation files.  The solution (turn off the Hibernation via the Terminal app) is NOT supported by Apple but it does help quit a bit.  Until Apple fixes this in their OS, this is the only solution I have found.  I too am running Windows 8 64Bit in Fusion.  (https://discussions.apple.com/thread/4029639?start=30&amp;tstart=0) go to page 6 and 7 of the post.  Good Luck