According to Mike’s measurements I linked above a cached Objective-C message send is faster than C++ virtual method call, so in a loop both languages should come pretty close. You can also get a pointer to the function implementing a method and call it directly. But I think we now understand each other – yes, Objective-C is not as fast as C++ in some cases, but those cases only matter to a very small number of people.
Also, it's _really_ easy to optimize those inner loops if you need to in Objective-C. If message passing is too slow, just turn it into some C function calls and you're done.
