Stutterless saves on Linux/MacOS using the fork syscall

[xor-bits]

Normally each autosave and manual save causes a huge stutter while the game is saving (like 1-2 seconds in a big map). This stutter could be eliminated on Linux and MacOS using the fork syscall to clone the game process (it is done by the OS with some magic to make it nearly free). The original process can continue running the game while the new process can save the game in the background (the background process won't see any changes to the game world because it will live in a snapshot).

This is basically what Factorio offers on Linux and MacOS to save the game without the lag spike.

One big problem with this is that Unity might make it difficult to do.