One thing I always do whether manual or auto battles, is wait until the end of the turn to do all of them. The reason is because of how much of a resource hog the AI is. The larger the map and higher the difficulty the worse it gets, mostly because of how many ships the AI spams. In most games I don't run larger than medium + high density because of this. That also means only running with 4-6 AI. All to reduce the effect of the their spam hogging all my computer's resources. If I go to a huge map with 8 AI even in the early game there's a significant system lag before I can actually issue orders or even add something to the queue in my systems.



This is with an Intel i3-2100 Sandybridge 3.1 GHz, 8 GB ram, GeForce GTX 550 Ti 1 GB vram, Windows 7 Home Premium 64 bit.

Here's something odd. This is the late part of the early game. The memory usage after watching a manual battle is actually less than before the battle.



Before battle.





After battle.