title: Are preg_match() and preg_replace() slow?
body: <p>I've been coding in PHP for a while and I keep reading that you should only use <code>preg_match</code> and <code>preg_replace</code> when you have to because it slows down performance. Why is this? Would it really be bad to use 20 <code>preg_matches</code> in one file instead of using another PHP function.</p>