Note that this works for big objects, but not for small objects. E.g. if you fork-share a large list of integers or dicts or something like that, then you don't get any memory usage benefits, because every access will cause a refcount-write and that will copy the whole page containing the object.
> * Technically it's O(N) for the size of data you have in memory at process pool start
It's not quite that simple; sharing n pages can take very little time or a bit more time; it depends on how the pages are mapped; sharing a large mapping doesn't take longer than a small mapping.
