Another factor to this is that during this 2.91 game getting enough money to raise the research % above 30% has been Much more difficult. Previous versions I can normally run 40-50% research early game, but not any more, nor can the AI it would seem. Late game I was always able to run 60% +.
The reduced gold from various techs, tile improvements, and buildings has a profound effect upon the available funds that can be allocated to research for player and AI. This all contributes to a slowed down research rate by all. Even with the cottage development line and money generated from it, it's just not enough money for research to keep pace with timeline.
Some food for thought.
JosEPh
I wanted to add a comment to the one made by this poster.
First the good stuff. I've been trying to play RoM since about v1.9 and have had an awful lot of fun with it. (Tried AND a few months ago and simply couldn't get on with it, the prehistorical stuff is too much and it crashed early in the game (about 3000BC). However, I've never made it to the industrial age before. Either the game crashed or I got the endless turn problem. So, this time I made it on a giant map all the way to 1898 before I got the endless turn problem. So well done, the game's more stable than it was and it's good fun.
Now the slightly frustrating stuff. As JosEPh suggests here, the tech accumulation rate simply can't keep pace with reality. On a recent game I was very lucky and had a good starting position, with plenty of resources and without any need to build a serious military. So I was able to divert all my spare points in to research. I had almost no fighting to do throughout the game. By 1850 I was on my fifth golden age and had in my 'research' city something like 450 research a turn and a total of 2,000 research per turn. But it made no difference, I simply wasn't able to keep pace. My industrial revolution was 100 years late, my renaissance 200 years late, my dark ages/mediaeval transition about 500 years late. By 1898 I was 450 points ahead of the nearest AI competitor (playing on prince). Most of the 20+ AI players were still developing astronomy in 1898.
I find that the AI players simply will not trade techs. At all. They flat out refuse, regardless of how beneficial this might be to them. I had a neighbour in the last game who was my bestest chum ever with +19 chumminess, and he wouldn't trade a technology.
So I wonder whether this is the main reason that tech growth has fallen off.
Furthermore, when I met other nations, almost every single one of them gave me a -1 for 'our close borders spark tensions' even though I was in one case 50 squares away.
Finally, I think that the 'captains' aren't an improvement to the game. They pick off units which are passing through territory, they steal workers if they can, and if I capture one in a neighbour's territory the same turn the neighbour captures it right back. And I think they're way overpowered, since I was facing 15-strength captains with axemen and I'm not sure how balanced that is. I would be inclined to get rid of them, with all the units available in the game they seem unnecessary.
Not sure whether this is helpful, I hope it is, but it is a super mod and I hope that you keep improving it.