When rumblings of how much processing power Kinect
used early on, the numbers of 10-15% didn't go over well with me. You're talking a lot of processing power being used up by a console so that it can decipher your movements. When developers are pushing the consoles nowadays to the limits, anything in that range would have significant effect on development.
Now, Alex Kipman of Microsoft has said
with their optimizations and Microsoft magic, they've knocked it down to the single digits. He doesn't say what the single digit range is though, but at least the CPU needs has been reduced. Originally, the camera had an on-board processor to handle the computations, but Microsoft removed it due to costs. Too bad as that would've relieved the 360's CPU of doing any of the leg work.
comes out tomorrow so the long strange road to release will soon be over and anyone will be able to flail away in front of their TV for fun, provided they have the living room space.