Is this really C++ specific though? It seems like the optimisations are happening on a lower level, and so would 'infect' other languages too.
Whatever the language, at some point in performance tweaking you will end up having to look at the assembly produced by your compiler, and discovering all kinds of surprises.
Whatever the language, at some point in performance tweaking you will end up having to look at the assembly produced by your compiler, and discovering all kinds of surprises.