It looks like you're already getting the right answer repeatedly, the best option for the engine you say you want is probably Godot. Godot is graphically powerful, memory efficient, and empowering to your creative freedom by not starting each new project file with a pre-built architecture that makes a bunch of assumptions about what you are going to do with it.
As you are a C++ coder, you may find Godot's "similar to python" GDscript very alien. C++ is like building a house by harvesting the trees and cutting the lumber yourself, and python is like telling the house to exist and *POOF* you have a house. But GDScript has big advancements over Python, which you'll no doubt realize if you go on that adventure. Godot's 2D engine also is about as efficient and powerful as you'll ever get.
The one big drawback of Godot is that there is nearly no learning material for 3D development. A few Godot users have made a few video tutorials demonstrating some conventions for how to do a few specialized things, but there is nothing out there for the essential basics. As an example, Godot uses it's own unique method of handling 3D rotation, but they have put out nothing that elaborates on how to actually use it to make your objects rotate. Godot might be the BEST game engine so far, and could prove to be the last one that ever needs to be created. But until they decide to open it up by producing some learning material for it, it is a big dark blob of mystery.
If you are able to permeate it, you will have achieved the extremely rare opportunity to actually take advantage of it. And if you do, please do the world a favor by sharing what you have learned, so Godot can become useful to more people.