Depends. My STL in C is faster by inlining the iterator methods. With something like glib or qt double indirection would be better of course, because these can be shared then.

In my jitted ruby-like VM my methods are also copied, not referenced. Javascript also prefers copying the methods. This is usually called prototype-based OO. True prototypes copy the struct fields also, without creating classes, but copying the read-only methods only is a worthwhile OO optimization, C++ cannot do.