Are blender modules like bpy already written in C? Would there be much benefit implementing cpp scripting?

I am currently playing around with blender derived game engines. Obviously, performance is a high priority. I am considering implementing c++ scripting.

I believe blender modules like bpy are written in c if i understand the docs. In which case, there’d be no need to rewrite/port then to c++. However, that also begs the question of how much performance benefits c scripting brings. I might be better off using bindings or I also came across a github project using eigen with numpy allowing very fast c++ ↔ blender python communication.