[G&K] AI turn very slow

Heya

I just played a OCC game on small map (6 AI, 10 city states or so) and especially at the end of the game the performance was terrible - each AI turn was taking about 30+ seconds which is quite annoying.
My system is pretty good:
Intel i5 quad core 3.3 GHz
8GB RAM

Any ideas how to improve these? I can't imagine how it would be on larger maps.

Thanks