SaverLoader (saver_loader.gd) can save procedural scene trees of arbitrary structure and rebuild them on load. It persists data from procedural and non-procedural objects – but only what you tell it to persist! Saves and loads are very fast because we don't save whole objects.
This system is used in I, Voyager (ivoyager.dev) to save/load a procedurally built Solar System with >100 planets & moons and up to 600,000+ asteroids. Our save/load times with an ssd drive are on the order of ~1 second!
For how-to guide, help and feedback, follow one of these two links to either the I, Voyager Forum or Godot Forum: