Well I never learn. I installed Parallels 6 on my present Mac in 2011 - i5 base model with 16 gig of RAM. I give it 3 gigs of memory and 1 CPU for first a Windows 7 then 8 now 8.1 installation. I upgraded from PD6 to PD8 and I'm now trialling PD10. Despite the promises of each iteration being faster than the last that's not my experience. When I click to start I get a black load screen for around a good minute followed by Windows desktop sluggishly finishing the boot procedure. I would estimate give or take the odd few seconds that the VM is not in a usable state before 1 minute 50 seconds has elapsed. That was the figure in 2011 and it's still the figure today with PD10. Fortunately I have a clone of the VM taken before I started this trial, needless to say I will be going back to PD8 forthwith. Given I'm not minded to update to Yosemite as I'm not keen on the UI then Parallels will not be getting any more of my hard earned cash. I've had enough of the hype that's never fulfilled.