This was on Road to War's Historical play as the US. Japan managed to conquer China and India, so you can imagine how many units they can pump out. The CTDs kept happening as I was trying to push out of Korea into Manchuria. Tried various things like restarting with different load orders but managed to stop them when I used 2 A-Bombs to remove a stack of somewhat-damaged units in an occupied Chinese city in western Manchuria. Thank goodness I had air supremacy in China. It's not like my recent laptop with 8GB RAM was struggling to run it either, and it was a clean crash. I suspect there may have been a problem with Japan's calculations of where to send those damaged units: heal, move, or attack? The Allied turns passed, as I saw the research bar ticking, before the crashes. It's a relief every turn when I see the "Autosaving" notification meaning no crash. May have to World Builder myself nukes if I really need it.