How does it compare to the old Quezler mod? https://mods.factorio.com/mod/rocks-heal-over-time-just-like-trees
Does it encompass more different things? Is the performance impact similar?

I didn't know this mod exists, that's why I made my own version.
I briefly looked at the source, and this mod uses a whitelist of entities that it heals.
My mod heals everything that is placed by the factorio map generator, so should also work all mods that add such entities.

My mod now has more performance impact, but I might switch to a method he uses to reduce it to almost zero (I was thinking about it already but don't have time to implement it now.)

Thanks for letting me know about it!

Yeah, no problem, I like to check for new mods and every time I see a possible double I always make sure to notify the author. You are not the first in this situation believe it or not! And alternatives are often cool to have.