Optimator has been under construction forever, and is nowhere near completion. That is what I get for trying to create a mod that surpasses even DYP without any help...
At any rate, here is the current terrain food stats I am playing with. Keep in mind I have nearly 200 resources I am using as well, many with food bonuses, and some of those 'bonuses' are of the
negative variety....
Terrain Base Irrigation
Desert 0 +1
Tundra 0 +1
Plains 1 +2
Grasslands 2 +3
Flood Plains 3 +1
Forests 1 N/A
Jungle 1 N/A
Swamps 1 N/A
Hills 1 +1
Mountains 0 N/A
Volcanoes 0 N/A
Coast 2 N/A
Sea 2 N/A
Ocean 2 N/A
I also assigned irrigation to a tech which becomes available towards the middle of the first era. This really makes grawth hard for almost all civs in the beginning - most cannot expand at all untill getting this tech, as most heavy food-based resources don't start becoming available until around the same time. If I play with over 20 or so civs, usually one or 2 will get an early population boom. Usually these are explorer civs, as their scouts will uncover extra techs or settlers. This is all fine with me, as I love the randomness all this creates.
You can also play with which techs and governments increase food production. You might want to make settlers more expensive (I did - about 35% more), although if you make it TOO expensive you will severely cripple the AI.
What I aimed to do in my mod was make expansion nearly impossible in the beginning, but slowly gets easier. By the time you are nearing the end of the modern era, about a third the worlds civs are absolutely booming, the second third is doing alright, and the last third is barely there.
You got quite a few options to control the AI Growth. Try them all out and see what creates the reaction you are looking for.