Measurable performance benefit? Or more a backend UX thing?

Problem/Motivation

Just came across this module and I'm asking myself if it would be possible to further explain how big the benefit of this module is in terms of performance. Or is it more a UX thing for the backend?

Would be nice to hear details, how much this for example "saves" for the bootstrap. Is loading unused blocks that expensive in core?
Are there perhaps core issues to remove these blocks or put them into optional modules instead, so they are only enabled if needed?

If anyone has further information to find out if it's worth to use this module just for performance reasons, it would be nice to put that on the module page.

Thanks :)

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes