vtable size/efficiency and 'final'

Consider a program that has a class Foo containing a function Foo::fn declared like this:

virtual void fn();

and a subclass of Foo called Bar. Will declaring Bar::fn like this:

virtual void fn() override final;

reduce the size of the vtable in instances of Bar and instances of classes inheriting from Bar? If so, what is the simplest, most efficient method to define Bar::fn such that its functionality is exactly that of Foo::fn?