Since doing a fresh install on my Vaio to Windows 8 pro my wifi has been playing up.

If I'm downloading a large file and I leave my laptop for longer than about 5 minutes my download speeds drop until move the mouse cursor again and it shoots back up.

I have tried putting my laptop into full power mode and updating my wifi adapter driver, but still no luck.

My adapter is a qualcomm atheros ar9285 using driver version

Any help would be much appreciated.