Well i tried another Game now. But its a bit curious. I play on Emporer now and well... the AI doesnt build many units, mostly obsolets one. On the last difficult, they allready had tons and tons of units in their citys.
What i also found a bit funny is, if you let the ai play for you, your civ gehts all the hammers and science bonus from the other civs! So your worker doesnt need 20 turns, only 6 or 7! And your science needs much less for the next new tech... Its only a minor problem, i know, but it shows, how the ai gets his huge stacks sometimes.
What i also found a bit disturbing, is the much bigger happy-face tolerance of the ai. I got a Pop 9 or 10 City and the AI allready has in the most Citys 15 - 20 or even bigger pop.
So my problem here is simple: On deity india - its everytime ing india conquers asia and africa and everything and has double or trippe of my points as number 2 and kills my middel-age army with gunfire and cannons or the zulu send a 80 units stack of doom (realy, 28 longbow, 25 - 30 mace-men, the rest spear and pikeman and 2,3,4 catapults lol)
On emporer i have no real problems till now, but maybe india will also conquer asia again and we have a nice late-game-battle.
Another problem i encounteres is, that the ai doesnt use much catapults if they are available. I build 10 - 12 of them and with them and their high tolerance against killing i kill every stack - even the zulu one - in 3,4,5 turns if i got 10,15 good macemen together.
Rebellion is quite useless as a game option for me: If i play a europe civilization, if i reach russia, its over for me, cause of Rebellions. India on the other hand, has most of asia and africa, even found citys there, and has Zero probs. No shattering of their empire, no rebellion, nothing.
Oh, i play on marathon gamespeed.
A last question: I encounter in the last 2 Games, that some techs are suddenly very, very cheap - i got a +XXX for science next to my own bulbs. Is this the "tech difussion" thing, which allows me to research things faster, because other civs allready researched it?