P.S. I have read the c++ code of finding best trade routes. There are tons of possibilites to optimize it. Saying it as pro in algorithms&maths. So, if the problem with trade routes in perfomance - I think it is not the problem, it is solvable.
I would love to see a solution to this. I'm sad that most players don't care about TRs just because they "seem" unmanageable.
If so we should remove espionage too, because I'm sure most players have no idea how to use espionage effectively and just forget about it.
If we were to remove all things players don't understand we will kill the hardcore gamers, because they only became hardcore gamers because they insisted on learning the mechanics to make the best use of them.
Trade Routes have a great impact on my CIV games for years now. I carefully choose who to OB with thinking on that, who to declare war, if it's interesting to change to Mercantilism or not (checking how much is the total Domestic TRs Values and the Foreign TRs Values).
I do agree though that TR choosing is horrible. Why do we *have* to get the best routes every turn? This shouldn't be like this, it's a lot unrealistic (I do think the game should focus on realism, but not only on that). If the mechanic is bad and unrealistic, it should be replaced by something More Realistic and/or with Better Performance.
But bonuses by connectedness still seem to me a bad replacement. Maybe it can get better, but I would prefer to see TRs being modified to enhance performance and also to be easier to understand for players who don't know how to manage them.
One point of difference is: With TRs you know who are the best partners, and there is a difference between declaring war against a good partner and a not so good one. With connectedness you just have to be sure you kept the max number your buildings/wonders need of foreign connectedness to be able to declare war economically unpunished on anyone. The Capital connectedness proposed by Afforess surely bring back some reliance on different AIs for economic boost, but it still doesn't make a difference between AIs as partners, just that it's better to keep in peace with the Max_Number of foreign capitals connected to your building. Above this number you're free to attack anyone again, and if it's below this number, it doesn't matter who you declare war against, all are treated equally.
About the Performance Issue val3, I was the one who started complaining about it. But I never reached past Renaissance on AND, so I'm not sure on this mod. But on LoR I tested an incredibly big mapsize with and without TRs, and while the first was really slow (like on huge Industrial era) to pass the turns when I had just developed the 2nd column of techs, the second only got that slow on Medieval Era. The increase on performance was incredible. My purpose with performance is to get even bigger maps then Gigantic. I'm almost sure most players never felt problems of performance on TRs if they kept to Standard Maps (but AND could have double the total TRs/city of BtS and LoR, so maybe I'm wrong).
If I'm not mistaken Embryodead did something with TR mechanics in his Sengoku Mod to support some 70 civs with lots of cities and still have a smooth game speed.