It reminds me of the good old C++ times, when people were scared OOP would make their programs unacceptably slow because of virtual functions. That's why method

It reminds me of the good old C++ times, when people were scared OOP would make their programs unacceptably slow because of virtual functions. That's why methods are not "virtual" by default, which led to nasty bugs when you were actually relying on polymorphism and forgot to declare a method virtual. Those were the days.