title: Memory usage when save value by References
body: <pre><code>$myStr = '';
  for ($i = 0; $i&lt;999500; $i++) {
      $myStr .= chr(rand(0,127));
  }
  echo round(memory_get_usage()/1024/1024,2) . ' Mb';
  </code></pre>
  
  <p><strong>I got 1.27 Mb</strong></p>
  
  <pre><code>$myStr = '';
  for ($i = 0; $i&lt;999500; $i++) {
      $myStr .= chr(rand(0,127));
  }
  $myStr2 = &amp;$myStr;
  echo round(memory_get_usage()/1024/1024,2) . ' Mb';
  </code></pre>
  
  <p>I save myStr to myStr2 By reference, and <strong>I got 1.27 Mb</strong></p>
  
  <pre><code>$myStr = '';
  for ($i = 0; $i&lt;999500; $i++) {
      $myStr .= chr(rand(0,127));
  }
  $myStr2 = $myStr;
  echo round(memory_get_usage()/1024/1024,2) . ' Mb';
  </code></pre>
  
  <p>$myStr2 = $myStr also <strong>I got 1.27 Mb</strong>. What's going on? Why I got 1.27 Mb, instead 2.54 Mb?</p>