Thanks to all of you for the information.
It seems the symptoms are mostly present in the 2.4GHz band in Windows* 8.1. I am not sure how many of you have a dual band router; perhaps it will be a better option to use 5 GHz while we work on the next driver release.
I can also see that disabling Bluetooth* and uAPSD has provided mixed results, which could mean the cause of the issue is not the same for everybody.