I don't think so. At a guess, the limitation is in the game server. Given how many users it has to support, it's likely that there's a maximum speed it can sustain in terms of serving users. And, btw, it's perfectly possible to have an excellent gaming experience at the speed you're talking about - my son is an avid gamer, our line maxes out at around 6mbps, and he has no problem. You may be suffering from extended ping times, which is a different thing to transfer rate.
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