title: Why is pop faster than shift?
body: <p>Douglas Crockford, in <em>JavaScript: The Good Parts</em>, states that "shift is usually much slower than pop". jsPerf <a href="http://jsperf.com/popvsshift">confirms this</a>. Does anyone know why this is the case? From an unsophisticated point of view, they seem to be doing pretty much the same thing.</p>