But not all mods are like this, some are simple. But when multiple mods are in play, it can get more complex still. You can see it notably when the turns progress and the processing spin indicator keeps spinning.
Perhaps this could by solved by having a maximum complexity limit per game? Each mod adds some complexity (Diplo mod adds a lot, my Press this Button mod very little), and a game is not allowed to have more than X complexity total. That should keep all games somewhat playable, and helps lower server resources.
This is obviously only worth implementing if people actually play modded games, which they still dont, so thats still a problem that needs to be fixed first....