virtualbox.org

I have tried using VirtualBox on both Linux and Windows Hosts.

On Linux, I ran into an issue with an older 3.0x VirtualBox release where multi-CPU guests were 2x to 3x slower vs. single-CPU guests. I asked in the forums, and the response was that there is a bug with AMD processors and IO-APIC. (This was a 2-CPU guest on a 4-core host).

I have more recently tried VirtualBox 3.04 on a Windows Host, with an Intel CPU. I was disappointed to find the same issue. Single-CPU guests were fine, dual-CPU guests horribly slow. Takes forever to do simple things in the guest, that are no issue on a single-cpu guest.

For now, I am using VMware player with a dual-CPU guest, created on another PC with VMware workstation.

I like some of the features (and the price) of VirtualBox, so I am still paying attention.

I think in 3.08 changelog, the AMD issue was "improved", but not fixed. The 3.10 changelog addresses a couple of more multi-CPU guest issues. So...question...if I try a new release of VirtualBox, am I still going to see performance issues with multi-cpu guests?

Yes, the multi-CPU support is MUCH improved in 3.0.10. It's still not quite as scaleable as native hardware, but is a dramatic improvement over 3.0.8.