If higher resolutions are slowing down the game, try 3200x1800 with AA Medium or Off. I personally find this resolution on the iMac retina displays a good mix of quality and performance on high settings.
If higher resolutions are slowing down the game, try 3200x1800 with AA Medium or Off. I personally find this resolution on the iMac retina displays a good mix of quality and performance on high settings.