Can you cache a virtual function lookup in C++?

Question

Say I have a virtual function call foo() on an abstract base class pointer, mypointer->foo(). When my app starts up, based on the contents of a file, it chooses to instantiate a

Answer 1

I asked a very similar question recently, and got the answer that it's possible as a GCC extension, but not portably:

C++: Pointer to monomorphic version of virtual member function?

In particular, I also tried it with Clang and it doesn't support this extension (even though it supports many other GCC extensions).