I have a 27" quad core i7 iMac that I bought in Nov. 2009. It has a ATI Radeon HD 4850 512 MB Graphics and 12 GB 1067 MHz DDR3 Memory. This has been a great computer except for playing my favorite game, Combat Mission. The problem occurs with large scenarios, playing or making scenarios. The game requires precise cursor placement on buttons and on the map to add roads, houses, terrain, etc. The cursor response to mouse movement is delayed over a second or so making the cursor movement jerky and difficult to accurately place on the screen. One feature of the game is using the cursor to move around in the game or scenario editor by placing the cursor at the edges of the screen. Many times the cursor disappears and appears at the wrong edge of the screen. I need advise on what next Mac I need to make playing this game more enjoyable?