Noticed today that my bluetooth mouse connected to my MacBook Pro gets nearly unusable when doing large file transfer to a nearby computer, the cursor is jerky and skips large parts of the hand motion.
This seems to be connected to Wifi vs. Bluetooth antenna interference, the jerkiness is significantly worse when my MacBook is in clamshell mode i.e. lid closed connected to external monitor. As soon as the MacBook lid is open the mouse cursor movements become smooth again. Problem goes away once file transfer is completed too.
MacBook Pro (15-inch, 2.53GHz, Mid 2009)
OS X 10.8.1