So I quite enjoyed the Districts in concept, but in the game they just tend to be a pain in the ass, adding an additional requirement to build trees and just making the game take longer. Especially since I enjoy more epic long-term games. Right now they are by far my biggest barrier to enjoying the game.
Sure you can heavily optimize production (or mod it to boost it, but ultimately I'd prefer to solve the core problem. What I'm interested in is a mod which
1) Greatly reduce production costs for districts, thus making them less of a drag on the game.
2) The ability to remove districts, or to build new ones. I don't mind if this would also remove the building improvements on the removed district (in fact it should do just that).
3) POSSIBLY the ability to allow all districts to have 2 per city instead of one. However, I can think of many balance issues this might cause, so it's really not a big deal.
It's just plain stupid that once a district is built, it's there forever, for thousands and thousands of years. Real cities change over time - residential areas become industrial ones or commercial and vice versa, especially when new, previously unknown, resources are discovered. Or wars or wonders drive a ruler to reshape their city in a grand way (Paris under Napoleon II for example).
Maybe demolition ought to be costly, but it should at least be POSSIBLE.
I think the first can be tweaked by just altering values, but I'm not sure how the second would might be accomplished?