I recently bought a late 2013 iMac, souped up to the max, it can play dota2 with max settings but still laggy .
GRAPHIC 065-C282 NVIDIAGeForceGTX780M 4GB GDDR5
PROCESSOR 065-C27V 3.5GHz Quad-core Intel Core i7
MEMORY 065-C1GM 32GB 1600MHz DDR3 SDRAM-2X8GB
HARD DRIVE 065-C222 512GB Flash Storage
But if I run in windows 7, in the same machine, dota 2 plays very smooth with all graphics settings max out! no lagg, smooth textures, high fps... everything a mac user (gamer) would wish to run the same performance on osX .. and thinking that open GL is way better that direct X...