Might be a little different from others however as one of the guy mentioned in the thread that the WiFi speed slows down in device active mode.

I can confirm thats happening with me too. I tried transferring a 18mb file with Winscp and the top download speed was 3MBps when device was locked and idle. However I tried to copy the same file again while keeping my N9 active by just changing the home screens and the speed dropped to 700KBps.

I know this test is not very reliable but still I can confirm that the speed varies in Idle & Active mode. This happen in both N & G mode.

As Jalyst suggested that a reflash can do wonders but I don't want to do reflash just because I don't want to set up my phone again. (Tired)

Can someone please guide me how they have overcome the above issue?

Cheers