set to the EU IP address in the background while you play, mind I am surprised you don't have issues playing on the US servers, given the nature of your connection.
will likely help give it a go.
Edit - with the game closed delete the file called DiskCacheArena just in case but doubtful.
From what i can see, from pingplotter, i have two problem:
1) Some DNS lose packet in some cases, but i think is a provider problem.
2) From all (even BW) i have huge jitters around.
Anything i can do to fix jitters?