I'm running Windows 8 on VirtualBox on Mac OSX. I wanted to enable iSight webcam and went to USB Devices, and ticked iSight cam. At this point the Windows becomes so slow it is virtually impossible to use. Any ideas how to solve that?
You probably have the USB device set to usb 1.1.
Follow this guide to download the USB 2.0 support pack
If it still does not play ball, Parallels has perfect USB support.