You mean bad frame rates? I think some people said they were getting bad FPS on "Shanty Town" and Roem's map "Sand Walls". It has to do with the # of polygons that were used to create the maps. People with fast computers don't have the problem. I assume if your Mac is 1.5ghz or faster that it shouldn't be a problem.
Everything runs at full speed on my 2.16 ghz MacBook Pro.