https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80826
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> --- For GCC 7 most time is spent in inlining. I suspect C++14 helps with constexpr evaluation doing some of the stuff in the frontend. integration : 21.73 (39%) usr 0.33 (23%) sys 22.02 (39%) wall 234388 kB (23%) ggc C++14: integration : 1.78 (14%) usr 0.16 (17%) sys 1.95 (14%) wall 99264 kB (17%) ggc one likely reason is that early optimization is not good at reducing abstraction with loops (not sure if std::map insertion involves loops that are optimizable). Maybe libstdc++ could still use features that make it faster with c++98 and only restrict its interface?
