Optimization examples "If you pass that by value one more time..." Use Const reference by default . Move semantic (TODO). Return value optimization (TODO). std::vector<> is your best friend Use std::vector<>::reserve by default "I have learnt linked-lists at university, should I use them?" Nooope . You don't need a std::map<> for that (TODO). Small vector optimization (TODO). "It is just a string, how bad could that be?" Strings are (almost) vectors When not to worry: small string optimization . String concatenation: the false sense of security of std::string::operator+ (TODO). std::string_view: love at first sight (TODO). Don't compute things twice. Example: 2D/3D transforms the smart way (TODO). Double for-loop: less elegant, more performant version (TODO). Fantastic data structures and where to find them. github地址： https://github.com/facontidavide/CPP_Optimizations_Diary