title: Returning by reference
body: <p>In the PHP documentation it says:</p>
  
  <blockquote>
    <p>Do not use return-by-reference to increase performance. The engine
    will automatically optimize this on its own.</p>
  </blockquote>
  
  <p>I wish to return a reference to an array (which is a property of my class). How does PHP optimize this, because the array is not an object? </p>
  
  <p>If the array has 1 billion entries, won't I get two arrays with 1 billion entries stored in memory if I don't pass it by reference?</p>