I have been testing a webcam setup with motion for a few weeks. I have been able to sort out all power issues by driving the camera via a powered USB hub. With the wheezy beta installed, everything worked fine, decent FPS (albeit at low res) and only ≈300 ms lag. All very good.
A couple of days ago, I upgraded to Raspbian expecting a performance increase. With my webcam (which by the way is a Logitech QuickCam E 3500) it au contraire. When I start motion, the raspi is choking! When typing a command, it takes a second to display each character in the terminal (all via ssh). The cpu load is not too bad, generally ≈30%, never over 50% so it doesn't seem to be that. The network traffic is < 50 k/s, so that doesn't seem to be the problem either. Killing the motion process brings the pi back to it's usual snappy self, all happy again.
Does anyone else have similar issues with Raspbian? Wheezy worked fine...