I see no reason why we can't have safe _and_ fast _and_ optional?
I'm actually glad to see you putting effort into making that happen. The effort required is the only reason. Performance wasn't the reason I don't use optional, but for those who do use it I'm sure it will be valuable.
The rationale you gave is just typical premature pessimization apologetics that also somehow assumes that C++ is "safe and slow" and that you have to go "bare metal C" to have performance. Luckily that's just plain incorrect, to put it mildly. Sadly, that rationale nonetheless also too often gives us such bloatware as std::streams, lexical_cast or boost::filesystem...
I said safe and fast C++ without optional, which isn't the same thing as "bare metal C". Bare metal C wouldn't qualify as safe. I'm as annoyed by the "C is faster than C++, ergo I never learned C++" guys as you are. Optional was implemented to be safe and slow because it was targeting safe and slow use cases. For POD types and anything that has a default constructor a std::pair<bool, T> seems fine to me. Regards, Luke