These days, it turns out that most obvious optimisations.. have already been done for you, either by the compiler or the CPU (both of which know a lot more about what your code is doing than you do).
Siku hizi, ni zamu nje kwamba wengi optimisations dhahiri .. tayari umefanyika kwa ajili yenu, ama kwa compiler au CPU (wote wawili ambao wanajua mengi zaidi juu ya nini kanuni yako ni kufanya kuliko wewe kufanya).