Well, I just played mission 6 for my second and last time. It was lagging so badly that when I went to juggle it literally took 10 seconds to sell a tower and try to buy another one. By that time a huge line of creeps were on their way out, and my game was over. I think it was around level 72 or so, and I had 18 lives left before this happened. I thought I might actually be able to beat it, since I was doing so well. There's no way I'm going to waste another hour trying to beat it, just for some stupid lag problem to mess me up. My internet connection is 1.5M down, just in case anyone's wondering.