These methods exist since the dawn of (open source) Godot and have hardly
been updated over time, so they barely work and I'm fairly sure nobody is
using them. (See #46505 for details.)
While some of the functionality they aimed to provide might be useful for
optimization work and introspection, this should likely be redesigned from
scratch with a cleaner and more modern interface (e.g. exposed via the
Performance singleton, or ResourceLoader, and a better API overall).