Hello mayors!
We have worked on a fix for the long loading times if you play with mods, and we would love your help to get more data points. We have opened up a Steam-only Beta branch where you can test out the hotfix that we are working on.
To opt in, you need to own the game on Steam, and follow the instructions on how to change your game version here and choose the 'loading_fix' beta option. This will start updating the game and will enable it. If you want to disable it afterward, swap back to the Default Public Version in the same menu.
If you have any more feedback after you have tested the branch, we would ask that you share it on our forum!