Is anyone NOT showing a performance drop on 2.4GHz wifi when Bluetooth is on? Also are you guys seeing the drop in speed just having BT turned on or is it only when you are actually paired to a device?
Well, yes and no. As I found out, the Marvell adapter speed was reduced by half with BT "on", compared to BT "off". You are correct: when no BT devices are connected, Marvell WiFi speed increases, in my case, double vs. BT device connected. (That is, 130 vs. 65 Mbps.)
However, an external USB WiFi adapter isn't at all affected by BT on/off status. (And it also connects at a higher speed == 150 Mbps.) The Marvell BT difference must have to do with the way the Marvell is constructed--AFAIK WiFi and BT are handled on the same chip, and BT "steals" from WiFi transfers. The USB adapter being completely independent of BT activity does not show the effect.
The only conclusion is that the Marvell WiFi/BT adapter is inadequate. Since it can't be replaced in our SP2 machines, unless/until there's a firmware fix, we're compelled to find workarounds--not a really satisfactory situation.
Perhaps a future SP model will have better WiFi/BT hardware, but then again, I can't afford to buy another device just to fix the bugs in this one.