Taking into account that nothing else in the game is lagging for me, I don't think that's strictly lag so much as the different mechanics. You don't move one square at a time in the arena; you move to the center points of each intersection. Add on to the fact that everyone else is moving as well, and the gameplay is slowed down almost by necessity so that you have a better chance of processing everything and formulating a gameplay plan.
...Of course, I could be completely off-base, but that's just based on observations. I figure indivi will let us know.