title: composer dump-autoload - command
body: <p>I don't understand the description of the <code>composer dump-autoload</code> command : </p>
  
  <pre><code>If you need to update the autoloader because of new classes in a classmap package for example, you can use "dump-autoload" to do that without having to go through an install or update.
  Additionally, it can dump an optimized autoloader that converts PSR-0/4 packages into classmap ones for performance reasons. In large applications with many classes, the autoloader can take up a substantial portion of every request's time. Using classmaps for everything is less convenient in development, but using this option you can still use PSR-0/4 for convenience and classmaps for performance. 
  </code></pre>
  
  <p>Why does it says <code>dump ... for performance reasons</code> ? Why dumping the optimized loader ? 
  Is it 'dumping for' or 'converts for performance reason' ?</p>
  
  <p>If it's 'dumping for performance', why then it says <code>classmaps for performance</code> ?  </p>
  
  <p>If it's 'converts for performance', why then dumping the autoloader  ?  </p>
  
  <p>I'm confused.</p>