Okay, I think this is as good a place as any to pitch the latest version of a suggestion I've made many times before. This time, I think I've come up with a solution that will please everyone. But I can't make a new thread for it, since it's inseperably intertwined with this idea.
Everything in the game should not be calculated per turn, but per year. Food/yr, Hammers/yr, Culture/yr. But between turns, multiple years pass. How many pass depends on game speed. This eliminates artificial inflation in harvest rates, research rates, etc. But the biggest reason is because this system allows the game speed to change in the middle of the game.
Now I suggested that the player could manually stop the clock to give a new order, but that made it too much like an RTS. So then I suggested that the computer dynamically changed turn length in response to important developments, which had many of its own problems. So now I have a solution that should go over well with everyone. Am I going to stop the build up and just say it? Yes.
The speed reduces time passage to 1 month/turn for any player in a war.
When you declare war or have war declared on you, every subsequent turn until peace is made with everybody will represent 1 month of time. Soldiers will move at a pace very close to how soldiers currently move in Civ IV. Meanwhile, every civ that is not at war will play at the normal speed. This means civs at war will take more turns than civs not at war, but the same amount of time passes regardless, and since everything is calculated per year, the increased number of turns doesn't change harvest rate, production rate, research rate, etc.
The effect this has is that, when the player enters war, he is practically locked in time, where progress in all areas is perceived to practically slow to a stop. The only thing that matters during war is arranging your troops and defending what has already been built. As soon as the war ends, time passage returns to normal, and you can go back to managing your empire like normal.
The other effect this has is that when other civs go to war, the war is typically resolved in very few turns, sometimes one. If you have the pleasure of watching the fighting civs through espionage, what happens can be rather surreal. Large chunks and even entire empires can seemingly disappear in the blink of an eye. Of course to the losers, the defeat was excruciatingly slow. Meanwhile, it's business as usual for you.