Factorio Forums

This behaviour is flaky, I can't reproduce it 100% of the time, but it appears regularly... I'll update this if I find a way on how to do it 100% of the time.

Basically I was switching back and forth between the factorio calculator (https://kirkmcdonald.github.io, using Firefox) and Factorio with Alt+Tab. Whilst the game ran fine in the background, it suddenly froze when regaining fullscreen focus.
As soon as you open the window picker with Alt+Tab again, the game unfreezes, even if you don't actually switch away from it.

Ambient sounds keep playing fine, although most machine sounds stop. It seems that only the game loop isn't running.
Also, I couldn't reproduce it in the main menu yet, there has to be an actual game running.

It has nothing to do with the factorio calculator website, although I had the impression it happens there more often.
I could just freeze the game whilst switching from the Factorio Forums to the game.

It worked 19 out of 20 times or so, so you have to be patient

Not sure if it is actually related, but my monitor has a quite unusual 32:9 form factor with 5120x1440 pixel resolution

It seems like the longer the game ran in the background, the more likely it will freeze