[Filligree]

> Also I've seen a project which persists large amounts of data to disk by forking and using a consistent snapshot of the data structures (which the new process will not mutate, so there's no need for locking).

It isn't an uncommon strategy. For example, the Factorio dedicated server can (optionally) do that if you're running it on non-Windows. The performance is great, but it's marked as experimental, probably because of issues like this article describes.