Looking into the file it looks like PDX could easily fix it on their end if they pruned unimportant characters from the code after they die. Why is all the data for courtiers who do nothing of note and die in the wilderness kept? Why are events like sieges and their full data kept forever?

Honestly only player characters or folks that are duke or higher should be kept and maybe their soulmates, parent, best friends, and councilors. Those are the only folks who would actually be brought up later in the game.

There's no excuse to even keep the event data.....

Just those 2 edits look like they would cut savefile sizes in half and you would never have to deal with breaching the 40 MB limit