This is actually a bad example because C style decls are provably, objectively, bad. They make parsing harder and once the types are non-trivial, they are absurdly hard to read and write. The case in point being non-trivial function pointers in C. The syntax for declaring a function pointer of a type that returns a function pointer is hidious.

The example is good, I just dont understand why you focused on compiler performance or developer experience. It doesnt imply program's performance.

We were talking purely about performance/energy eff of generated binary, not other RELEVANT things like developer experience/low compilation times because it is outside the scope of this discussion.

Yes, C++ is poorly designed language, but point that syntax (letters) don't imply language's performance stands. The result is up to the implementation: compiler, runtime/vm, std libs, etc.