Most C++ Virtual Calls Are NOT Dynamic Dispatch

Most people believe that C++ virtual functions are inherently slow because they rely on runtime vtable lookups. This explanation is not wrong — but it’s dangerously incomplete. In this video, we go far beyond slogans and textbook diagrams. We break down virtual function calls from three core perspectives: -ABI specifications (Itanium C++ ABI) -When and how vtables are actually generated -How modern compilers devirtualize virtual calls You’ll learn: -Why vtables are fully generated at compile time -Why a virtual call is just a fixed-offset indirect jump -How CPUs can accurately predict most virtual calls -When virtual calls become real runtime polymorphism -How final, optimization levels, and LTO eliminate dynamic dispatch entirely If you care about C++ performance, compiler behavior, ABI design, and how code really executes on modern CPUs, this video is for you.