So I tried downloading a mod onto my user on my mac. It didn't work and it made my game crash at the loading screen. So I transfered ay maps onto Macintosh HD in finder so I could play on another user on my computer with an untampered version. On the original user the game was hardly laggy at all, but on the new one it starts out perfect then after like 2 minutes it gets unplayable. I've tried setting all the video settings and stuff, I also changed the java runtime, I even changed the two things in the content info to "true".
its on 10.6.8 and its the 21.5 inch imac bought i think two years ago