Virtual functions performance cost

From Efficient C++ Performance Programming Techniques:

Virtual functions seem to inflict a performance cost in several ways:

• The vptr must be initialized in the constructor.
• A virtual function is invoked via pointer indirection. We must fetch the pointer to the function table and then access the correct function offset.
• Inlining is a compile-time decision. The compiler cannot inline virtual functions whose resolution takes place at run-time.