Can't install freebsd inside virtualbox, glacially slow

[Quartz]

I can't seem to get the 10.1 installer to work under virtualbox, 
everything is so slow it's completely unusable. The dvd image takes 
upwards of a minute to even draw the opening ascii menu, and attempting 
to boot the kernel just sits there forever. If I convert the memstick 
img into a vdi and boot from that, I just get the "spinning slash" 
forever (it doesn't even get to the menu). I've tried the 'set 
vfs.unmapped_buf_allowed=0' trick, tried changing vb's chipset from 
PIIX3 to ICH9, tried changing the number of CPUs and ram and everything, 
but no dice. Anyone have any ideas?