Why are greedy quantifiers less expensive than lazy quantifiers
<p><a href="http://www.rexegg.com/regex-quantifiers.html#tempered_greed" rel="nofollow noreferrer">http://www.rexegg.com/regex-quantifiers.html#tempered_greed</a></p>

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<p><strong>Greedy quantifiers</strong> (default) - work by swallowing as many characters allowed before slowly reducing the amount of characters matched one-by-one in order to make way for the rest of the pattern. </p>

<p>For example, the regular expression <code>.*world</code> against the string <code>hello world</code> will first attempt to swallow the whole string and put it into the <code>.*</code>. But it cant, because then <code>world</code> cant match, so <code>.*</code> starts giving up characters one by one until it has given up the <code>world</code> in the original string - in which case the whole regex can match.</p>

<p><strong>Lazy quantifiers</strong> - work in much the similiar way, except in reverse. They want to match as less characters as possible, and they do the same thing, adding more characters one-by-one until the rest of the pattern has a chance of matching</p>

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<p>But according to this article I read, these seemingly identical processes for <strong>greedy</strong> and <strong>lazy</strong> quantifiers are different - in that only <strong>lazy</strong> quantifiers have the need to "backtrack". But wouldn't <strong>greedy</strong> quantifiers also need to "backtrack" when spitting out previously swallowed elements?</p>

<p>Why is this the case? It just seems so intuitive </p>