Why is processing a sorted array faster than an unsorted array?

This is the 20th submission of the same Stackoverflow link. The previous one with the most comments, at 120, is <a href="https://news.ycombinator.com/item?id=4637196" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=4637196</a> .