My WiFi is still incredibly slow. I've posted about it here before and I've tried everything that's been suggested. I've even tried using different routers and
homemade signal boosters. If you're interested in making homemade extenders/boosters, see
this also. It explains it well in theory.
Personally I've just given up on the Nexus 7 wifi. If I have something to watch rather than try stream it I'll download it and push it to the Nexus 7 wirelessly with
Airdroid. I have issues with reddit (especially when using 3rd party apps like baconreader to access) and facebook (app and mobile) not even receiving data. I have to actually turn the device off and restart it just to check my news feed.
I was thinking the other day that the problem may be heat related. The heat from games and the battery charging (battery is in close proximity to wifi card) may of damaged or somehow distorted the card. It's possible that it's worked itself loose also but I assume that would result in terminal failure rather than patchiness.