I am noticing that whenever I have my bluetooth headset on using the Note 2, the wifi speed degrades considerably. If you are listening to an online song stream, you may not notice as song does not take that much bandwidth for streaming, but if you watch an HD youtube video and listen using bluetooth headset, the video keeps getting stuck waiting for buffering.
Anybody else sees the same problem with Note 2? I am strongly suspecting that it is some sort of bluetooth intervention with wifi that degrades wifi download speed considerably. You could do this experiment by checking your internet speed with/without playing a song over bluetooth headset, and you would see the difference in download speed.