I've been reading through Unreal's 'Saving and Loading' guide: Link
Within, they present a capability to save a game to main memory rather than secondary storage:
I haven't found any information on where this would ever be used.
The only situation I can fathom for this being useful is to keep data about other load zones in memory so that travelling through load screens into these zones is quicker.
Why, When and Where is this technique of saving to Main Memory used instead of saving to Secondary Storage?