Just recently I started to have a very odd program with LoL.

When LoL is not running, my internet works great, no problems at all (even with other online games, my ping is great).

As soon as I open LoL and get into a game, everything starts to slow down dramatically, not just for me, but for my whole network as well. As soon as I close LoL, everything goes back to normal.

I looked around on this site and opened all the suggested ports, and it helped a little, but the problem is still there.

Anything else I could try?
I hope my hardware isn't dying, but its always a possibility.