DragonFly has been unable to work on VirtualBox for quite some time due to a timer problem. However, the VirtualBox developers have come up with a patch that fixes it. It’s not in the VirtualBox 2.1.2 release, though I assume it’ll be in the next one after that.
A running description of activity related to DragonFly BSD.
Excellent, this is great news.
I’m using 2.1.4 right now and not seeing any improvement.
The bug page for it says the patch is “not entirely approved”, though I’m not sure what that means. That’s a question for the VirtualBox developers.