title: app.use(express.static()) at the end of the program
body: <p>As far as I understand when I use <code>app.use(middleware)</code> this middleware will be called on every request on a server.</p>
  <p>So when I use <code>express.static()</code> as a middleware it will to be called on every request too but in this case it's not needed to be called on any request so why do I need to put it at the top of my program? I haven't seen anybody puts it before <code>app.listen()</code>. Why is this so?</p>
  <p>Does it cause any performance degradation?</p>