Already tested. When you first connect to the wifi everything works as expected. As time passes wifi speed decreases.
While moving files in a 802.11n connection im getting 10 to 11 mb /s . An hour and a half later I'm getting 2 to 2.5mb / s. If I turn wifi off (via charm bar) and back on I get full speed back.
Im using the old Marvell drivers dated april 24, but I also tested it with new ones (jun 20) with the same results.
I'm getting this exact issue.