I am interested in this too, as the problem started occurring 2-3 weeks ago for me too (I think on a Sunday it started).
I already opened up a thread myself but am interested if you fix it too, as seems to be related, so I'm following this thread
Having the exact same issue. The bandwidth is complete garbage recently, phoned support and they have no clue what I'm talking about. Ran some tests, apparently, and did nothing about it despite asking for an engineer to be sent out.
Do a Google search for "netflix causing games to stutter", its a very common problem.
There is nothing you can do on a BT Home hub, this has been discussed on many other threads.
I believe its related the amount of information that Netflix uploads while a stream is playing, which is delaying the commands you are sending to the game server.
People have had some sucesss by lowering the quality of the Netflix stream to SD, and restricting the upload speed and priority of the device which is doing the streaming, by using different routers which support these features.
It goes without saying that using a wireless connection will be no good anyway, as that has lots of issues with interference.
The Internet providers are more interested in promoting Value Added Content like streaming TV and video, as that is where the money is made.
I suspect that if people want to do a lot of gaming, they are going to have to get their own dedicated connection in the future.