Recently my big battles (seems to become worse the bigger the battles) have been causing hangs. Sometimes the FPS will drop and then it will hang for several minutes. The game will just stay there, halted, and my CPU/GPU fans slow down. When it happens I just ALT+TAB and wait it out and I can tell it's "back" because I hear my fans coming back to speed. I can then usually play for a minute or so before it happens again and hangs for another good 10-15 minutes. I noticed it happens when the enemy starts fleeing and only stops once there are no more fleeing units.