Well, civ uses quite "old" engine. And if you're using a rather old computer, it's even slower. But could you give me you save game? I'll try to look what is consuming so much time when I find some free time.
BTW, how slow the turns are?
when I started war against Austria-Hungary it dropped down to something like 1 min... (didnt sit down with watches!).
Usual peace turn in my current game (yeah I started again some other game) is around 20secs. One would say it's reasonable, but for me it's killing fun.
And no I am not using old computer... It's mainstream now, amd phenom II, gf 9800 gt.
I agree that civ generally is slow, but the times from start are on par with turn times in really late game with maneuvering sods of 50+ units and managing empires of 10+cities (and have to say late game is not my favourite time of game and usually abandon games much earlier ;-)).
In attachment is the save.
I think you can't do anything with it, since it's nothing wrong with you probably. It could be trade routes calculations. (I saw it somewhere mentioned that turn times are much afflicted with calculating trade routes and best trade routes, and the more you have them and possible trade cities...you can imagine... it's at least quadratic computation (didnt find equivalent for czech term... it's measurement of complexity of computation in IT...)
edit:
i can confirm that when you or someone else enters war then it really drops the turn timer a lot... right now Austria DoWed Australia in my current game and well it was a long long wait...