I've read several posts saying that there is a cap of 4 turns / tech, that you can not research tech any faster. I can say that that is false.
I've researched techs at 3 / game and I'm still early in the 3rd age. I just barely researched Sanitation, and I think that as my cities get bigger, I'll be able to possibly drop it even to 2 turns / tech.
There is absolutely not a low end cap on tech (at least not 4/turn). On Regent, just having now entered the Middle Ages I can achieve 3/turn tech. There is a high end cap of 32 turns per tech.
I agree, I too have gotte down to 3turns/tech in the middle ages.
I have another question though. In civ ii, extra beakers after a discovery went towrds the next tech you chose to research. Does anyone know if that is the same in civ iii? Don't answer here I will post it in another thread.
I think I started that myth. After more testing I found I could get a 3 turn tech. Its just getting a 4 turn tech is much easier than getting a 3 turn tech.