[hcal]

I'd check your RAM settings first. A faster processor helps, but to virtualize an OS properly you need a good chunk of RAM to make both Host and Guest feel snappy. Four gigs works well for me without a VM running, but is a little laggy once a virtual OS is spun up. With my typical work load and 8 gigs of memory properly allocated between the host and guest OSes I rarely notice the VM running in the background.

[jiggy2011]

My host OS still feels fast enough with the VM running. It's just stuff like menu draws and window dragging etc are very far from snappy. Throughput doesn't seem to be the issue so much as latency.

Possibly a graphics issue, though I do have a reasonable nvidia card and enabled 3d acceleration in Virtualbox.