Efficiency has always been important to programmers. It is one of the key pillars in the tradition of C and C++, in which the guiding principle of "you shouldn't pay for what you don't use" ”also known as the zero-cost principle ”has always been at the forefront of the language's and library's design, and has been largely achieved.
This section, along with the two appendixes at the end of the book, takes a hard look at a few key C++ optimization issues selected for their real-world impact. When and how should you optimize your code? What does inline do, really? Why can (and do) fancy optimizations get us into trouble? Finally, and to me most interestingly, how can some of these answers change if you're writing multithread-safe code? After all, we're interested in efficiency issues in the real world, and although the C++ standard is silent about threads, more and more programmers in the trenches are writing multithreaded C++ code every day. And they will care about the answers.
