[MetalMilitia]

The thing is as far as I'm aware there isn't really any mechanism through which the router could give your computer preference in Internet bandwidth and I certainly wouldn't expect random HTTP requests to max out the available bandwidth.

I think the next thing to do would be to identify which machine is actually the problem by adding a third device to the network and identifying if it causes the effect on your house mate's machine, or duplicates it.
Perhaps you could ask a friend to bring a laptop over or something (even a wi-fi phone might work).