Forgive me if this has already been discussed, but I thought it was of interest...
As I am hanging out with family for the holiday, 3 of us had some Mario Kart DS action going on and another person fired up the cube to play some Wind Waker...
Much to my surprise, as soon as he started playing cube, with a Wavebird on channel 3, we saw an extreme framerate drop in our Mario Kart match. He flicked the wavebird on and off, and sure enough, the frame rate drop went right along with the wavebird. This wasn't a small drop either. I'm guessing our race was chugging at between 10 and 15 fps.
Has this been documented? I'm going to do some more experiments with different wavebird channels to see if it keeps doing it.