It's very strange then, since as soon as i started the war, the game auto-saved with the on-screen text and associated slowdown.
I reloaded the game after crashing it, and the game loads into the exact moment when it said that it was saving after the wardec.
And you cannot even change the autosave options for inonman games.
Are you sure that you ran your test in ironman?
Does anybody else have the same experience in ironman games, that the game does not auto-save on war declaration?
It depends how far along you are from the last save, not in days, but in actions.
Sometimes it can save several times shortly after each other, if massive stuff is going on. Other times you can run an entire month, declaring wars, making alliances and all that jazz, and it still won't save before start of the month.
Something like a PU between majors will almost always save instantly, as will the burgundian inheritance most often, though not always.