virtualbox.org

I am seeing a huge performance hit for running a Windows XP guest with 2 CPU's + IO-APIC enabled vs.1 CPU and no IO-APIC. Just a quick test, boot time for the 1 CPU guest is close to 30 seconds. Boot time for the 2 CPU guest is close to 2 minutes. I didn't time the install times, but it was much faster on the 1 CPU guest. As a guess, something like 15 minutes vs. 30 minutes for the 2 CPU guest.

Is this typical? Is the behavior the same for Linux and other hosts for 1 CPU vs. 2 CPU?

That was just some quick benchmarking. When I have time, I will try a few others.

System info: AMD Phenom 945, 8 GB RAM, 7200 RPM SATA disk, Xubuntu 64-bit as host OS
Both XP guests are 32-bit, 2GB RAM, 32MB video RAM, fresh installations. After installing the 2CPU guest and seeing how slow it was, I created and installed the 1CPU guest, trying to go through the same installation procedure. (I think the only difference is that I selected quick format for the disk on the 1CPU guest vs. the other option for the 2CPU guest)

Thanks!

It is known that the performance isn't what it supposed to be. The feature is new and still not fully developed. Expect improvements over the next releases, it should go a lot faster in the future.