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I am running 64-bit Vista with 8 GB ram and 4 cores. It supports hardware-assited virtualization.

Using Virtual PC 2007, my newly built 32-bit Windows XP Pro VM is running incredibly poorly. Even the simplest actions like showing the start menu will cause the CPU usage to hit 100%.

The same VM setup hosted on a dual-core 32-bit XP Pro box without hardware-assited virtualization work just fine.

Any suggestions? Right now it is almost unusable on my Vista box and I don't even know where to start looking for the cause.

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up vote 3 down vote accepted
  • Enable Hardware Assisted Virtualization in the BIOS.
  • Install the VM Tools on the guest OS.
  • Run your VM's from a separate spindle if you can. A lot of times the bottleneck is disk.
  • Give VM's the right amount of memory for the task. If the VM is constantly swapping it can play havoc with performance.
  • Make sure the host and guest operating systems are defragmented.
  • Cut off fancy gui effects on the guest systems.
  • Exclude your .vhd,.vmdk and associated files from the host systems active anti-virus scanning.

Just a few tips that should help. By the way I have the same exact setup on my desk as well (Quad Core Intel Q9400, 8Gb RAM, Vista 64) and have been using Vmware Server 2 with multiple VM's without issue.

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The VM has 1.5 GB of ram, VM tools, and no anti-virus program. I don't have a secondary hard drive, but if the BIOS thing doesn't work I will look into getting one. – Jonathan Allen Jun 4 '09 at 2:29
Defragging didn't help. I will double-check the GUI effects. – Jonathan Allen Jun 4 '09 at 2:31
Looking at the host computer's performance counters, the Disk I/O was really high. I killed off everything I could that touched the disk, including the page file. It is still slow, but it is at least usable. – Jonathan Allen Jun 4 '09 at 5:52
I know you mentioned that the VM has no anti-virus, but does the host machine? Most anti-virus products have some type of real time scanning that can go active when the vhd is being utilized. Also are you using difference disks? A coworker mentioned he was experiencing heavy disk use and performance issues when utilizing a chain of difference disks for some of his VM's. If you are you may want to merge the changes into one new vhd, if that makes sense. – Shaun Hess Jun 4 '09 at 17:42

Are you sure that the Virtualisation technology is enabled in your BIOS? Your setup sounds identical to mine (Quad Core, 8Gb, Vista x64) and I run dozens of Virtual Machines (albeit VMWare) without it missing a beat.

As an experiment, I turned Virtualisation off and found performance was greatly hampered.

That would be your first stop - checking to see if it's actually enabled in your BIOS.

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I was under the impression that the hardware virtualization checkbox would be disabled if it was turned off in the BIOS. Still, I will investigate. – Jonathan Allen Jun 4 '09 at 2:30
Possibly, I'm not sure - I haven't used Virtual PC in a long time... – Mark Henderson Jun 4 '09 at 2:37

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