Why defining class as final improves JVM performance?

Question

Quoting from http://sites.google.com/site/gson/gson-design-document:

Why are most classes in Gson marked as final?

While Gson provides a

Answer 1

Not knowing the implementation of every particular JVM, I would theoretically say that if a JVM knows that a pointer to an object is a pointer to a type that is final, it can do non-virtual function calls (i.e., direct vs. indirect) to a member functions (i.e., no indirection through a function pointer), which may result in faster execution. This may also in turn lead to inlinining possibilities.