CtD on first turn of a save

Hey all. Recently on Civ V I've encountered a rather bizarre issue that is rendering some of my games unplayable. The game runs fine for good number of turns (I'm on historic speed, so I mean around 100 turns). But starting around then, when I load up a save, quite often the game will crash almost immediately after hitting next turn. The problem is only ever on the first turn of a save - if I pass the first turn, it will definitely work until I save and quit and reload again. What's especially odd is that this will even affecct turns I've played through already withotu a hitch - ie, if a save isn't working, I'll head to a recent autosave and have the exact same issue - crashing on the initial turn of that save.

If I do manage to find a save that works and go a bit further often the next save or two I make will be okay, but the problem inevitably returns every two or three saves or so, seemingly worse the further through the game I get. At turn 230 it's proving unsustainable. I really have no idea what could be causing an issue as specific as this, but I've tried turning of core threading, lowering graphical settings completely, playing in strategic view, using a different DirectX - all to no avail. I'd be very grateful for your suggestions on how to tackle this. The only mods I am using are a number of British civ mods (all seemingly pretty stable), historic speed, IGE and historical religions.

Thanks!