Heh, you increased the cost of cultural centers?
It already takes about a hundred years to create a CC even on a homeworld with five billion people...
I'll just say that if you're planning to play 100 years against the computer, I'd recommend patching to 1.5 when it comes out, because the AI will do a much better job of doing something meaningful in the meantime. In 1.3, after 100 years almost all their colonies will have nothing on them but a CC under construction at about 25% complete, I would think. 1.5 will fix this, but you'll have to re-apply your tweaks.
PvK