That quote about premature optimization is from 1974. Back then, manually tweaking code to produce the "right" machine instructions really mattered. But it was

That quote about premature optimization is from 1974. Back then, manually tweaking code to produce the "right" machine instructions really mattered. But it was time-consuming and hard, and hence should be applied only to the most time-sensitive part of a program. Today, we get that kind of optimization, for the whole program, simply by adding -O2 to our build options, and waiting slightly longer for the compiler to complete. Engineers using that quote are an important reason for the failure of software projects. Not only should we make efficient use of resources, but performance of software must be taken into account right from the beginning of any software project. Performance requirements must be clear from the start (how many concurrent users, how many requests per second, etc., times 2 (or 20) for safety) and when a design is made, performance requirements for each individual component should be set (and measured after implementation).