I had the same issue and wanted to give this a try and set the boot flag. When I started my Windows 7 the Parallels Tools were reinstalled and to my surprise the CPU usage on my Mac was now very low (average of 1% when Windows is idling in background and 7% when Windows is in foreground). Then I wanted to confirm that it had something to do with this boot flag and removed it again and the Parallels Tools were reinstalled again as well. But now CPU usage is still low even after doing some work. So maybe it was just something wrong with my previous installation of Parallels Tools?
Word of advice: During Parallels Tools installation Windows will ask you to reboot. Don't do that but wait until the installer finishes and then prompts you to reboot.
My setup:
- MBPR 15" Mid 2012, 2,6GHz Core i7, 8GB RAM, Nvidia Geforce GT 650M 1024MB running OS X 10.8.5 (12F45)
- Parallels Desktop 9.0.23136
- Windows 7 Professional 64 bit (Build 7601) installed via Boot Camp and running from Boot Camp partition
- 4 out of 8 cores assigned to VM
- 2GB out of 8GB RAM assigned to VM
- Hardware Video: 512MB out of 1024MB assigned to VM, DirectX 10 3D Acceleration, Vertical Synchronization enabled
- Optimization Performance: Faster Mac, Adaptive Hypervisor enabled, Windows tuned for speed
- Optimization Power: Better performance
- using Window View
Hope this may help someone as this CPU usage thing was really annoying.
edit: Added screenshot of Activity Monitor showing my now nicely running PD.
Last edited: Oct 22, 2013