Game crashes every 30 mins to an Hour (macOS)

Crashes after a set period regardless of game situation are likely to be overheating or a memory leak. And will 64gb of memory I'm pretty sure it is not the latter.

If you re-load the same save immediately after the crash can you play for another 30-60 minutes, or it crashes sooner - or even won't load at all?

How about if you start a new test campaign at that point, what happens?  

Then this may be the issue discussed here

CK3 crashes in game (macOS)

CK3 crashes in after 1h of game play . the game closes and exits. crashreport is not working. if I start again the timer until crash gets shorter. restart of computer without any help. I recently turned off the autosave and any steam cloud sync... forum.paradoxplaza.com
All I can guess is some internal memory buffer in the game is exhausting, so effectively a memory leak but within the game so no amount of system memory helps.

Please add your report to the one that user is make in Bug Reports, or start your own if you wish.

Sorry for the problem!