Function pointers / vtables / polymorphism are slow, because they're indirect jumps (harder to predict). Function calls are slow, because there's work to do to

Function pointers / vtables / polymorphism are slow, because they're indirect jumps (harder to predict). Function calls are slow, because there's work to do to save / restore state on the stack. These don't matter much for big heavy functions, but tiny ones can seriously benefit from being inlined. I have heard elsewhere that "game objects are just an index into a bunch of arrays for all the object properties" is fairly common practice, but well I don't write games myself.