Snow Leopard + Windows 7 + Parallels 4, Extremely slow

After spending much time trying to get the right configuration for my Windows 7 VM, the situation seems to be getting worse. It takes 35 min to get fully started up and tasks as simple as emptying the trash take as long as 12 minutes to complete. I can't disable any more features and I've stripped Windows 7 to just the bare minimum. At this point I don't know what to do to make this usable.

Any suggestions would be greatly appreciated. Thanks in advance.

Computer: MacBook Pro, Intel Core 2 Dou, 1 processor, 2 cores, 2.4 GHz processor, 4 GB memory, 25 GB drive space available
Host OS: 10.6.3
Guest OS: Windows 7 Professional
Parallels Desktop Preferences: 2024 MB manually allocated; transitions, animations and sound disabled
Virtual Machine Configuration: Adaptive hypervisor disabled, optimize performance for virtual machine, optimize power consumption for better performance, 2 CPUs used, 2048 MB memory, 16 MB video memory, shared folders disabled, shared profile disabled, shared applications disabled, smart mount disabled, smart guard disabled, floppy disk disabled, cd disabled, sound disabled

 

You have 2024 MB allocated to Parallels but are trying to run a 2048 MB VM... sounds like the poor thing is forced to swap a lot. I suggest: Assign just one CPU to the VM, assign just 1024 MB to the VM, assign 1024 MB to Parallels overall (or set to Automatic). How large is your virtual disk drive?

 

Adjustments that are improving speed

After trying the previous advice, I settled on:

Manually assigning 2048 MB to Parallels Desktop
Giving the VM 2048 MB and using 2 CPUs

This gives me a start up of 5 minutes and decent responsiveness. As to this advice, though, I see big differences in the amount of success people have with this software. Some people claim to have it installed on Air with perfect functionality, while others have it installed on MacBook Pro with little functionality. Either the claims are just not true, or this is highly unstable software.

Why is everyone guided to only use 1 CPU, wouldn't 2 make it faster? Is too much RAM a bad thing? The advice given on this forum seems like voodoo to me. Is there a best practices document on configuring that has solid reasons why certain scenarios are better than others? I appreciate the advice, but I always see the advice being to lower memory, use less CPUs, use automatic memory assignment; all of which flies in the face of logic. Is there any reasoning behind this advise, or just a hunch?

 

I'm using a Windows 7 64bit Parallels VM on an MBAir and it runs quite nicely. I can't really run a 1 GB VM off the Air's internal drive, though, as it'll seriously start to thrash when I try to do things on the Mac side and in the VM in, well, parallel. So I'm running two VMs - one is an 864 MB VM that sits on the internal drive; 864 is just about the maximum that the Air will tolerate with one or two smallish Mac apps open (Entourage and maybe Preview).
I also have a 1 GB VM that sits on an external USB drive; that is quite a bit faster on the Air, presumably because its internal drive just isn't very fast, and the Mac and the VM aren't fighting each other for disk access.
Yes, 2 CPU would make the VM faster BUT at least on the Air (and I guess this is true for other MacBooks) the Mac OS will shut down one core when it feels the CPU becoming too hot. However, the VM doesn't get that (as far as I understand) which then really bogs down the VM - it is expecting 2 cores to run its threads but gets only one of them.

My reasoning for going easy on the VM is: The less memory the higher the chances are that the Mac (which is the boss system) doesn't have to start swapping. If you use less cores you'll have a lower likelihood of the Mac shutting down one core. Automemory... I'm not sure about that one; frankly, I don't really see a difference between automemory and manually assigning 1,024 MB to my 1 Gig VM. Optimise for the VM - if you have the RAM to spare, go for it, else it may actually slow down your Mac as it'll more likely start to swap memory out to the disk. And since the Mac is boss, when it starts swapping, the VM has to wait -> spinning beach ball and -> go grab a coffee while-u-wait.

At least that's what I've learned over several months of running my VM. Your results may differ