This seems to have been posted a thousand times, but it's a serious problem. I've attached a couple of screenshots showing the activity monitor of the host OS (Mountain Lion on a MBP Retina) and the task manager of the only guest OS (Windows 8) at the exact same moment. 1% guest/46% host. It's just impossible to get any battery life this way.
I have this experience with two different VMs and with two different MacBooks (one an older 2010 model).
I fully acknowledge that the guest OS does have some impact on the host utilization, but the lowest I've had it hover around is 25% (on a 4-thread machine, making me think it always pegs one core). Also, I acknowledge that what the guest OS has installed matters. On a fresh install that does nothing, I think I had lower host utilzation(maybe 8%), but once I have things installed I've never had lower than 25%. So, here is a list of software I suspect might have an impact. But keep in mind that even with all this installed, it doesn't change the fact that 1% somehow turns into 46%, which seems extreme. It's not like my guest is "idling" at 10% or something.
- SQL Server
- Crashplan
- Dropbox
But, I can't consistently observe a drop in host utlization by killing any of the above processes.
Anyway, this is a hugely annoying problem and the user'
s ability to figure out what is actually causing it is very limited. And that's why there have been dozens of complaints about this problem over the last several years.