I know this has been posted several times. I just want to post my suggestions, I really like to play the game and finish it.
The game performance definitely still need improvement. The point is that no computer in the world can handle it this well. The game will just slow down at later stage, especially with deity difficulty. Each and every AI will just have so many units and slow down the turn time so much that I have to put a book beside my computer, and start reading it when my turn is finished.
Can the dev start looking at this please?
From my observation, at the AI turns, their military units just move around randomly every time. Why can't you just make them station around some cities or borders while not in war? I think this is the main bottleneck for the long waiting time per turn. I'm pretty sure it will boost up the speed significantly. And it sort of make them look smarter that they are always prepared for war. Of course, it might still slow down when war actually occurs, but that's understandable, and should speed up reasonably quickly when their units got cleared up.
If I'm wrong then too bad.
This might involve a major code re-development, in terms of Object Oriented systems, all the military units should just be an object under a leader object. And only when he's at war, or threatened by barbarians, or when he needs to expand to a new land (escorting the settlers), then only his military units should be mobilized. At other times his units should just be stationed at cities or near borders.
Please, I would really like to finish a Deity game in huge maps, with domination victory condition.