title: usort order string by length optimization
body: <p>I'm coding a program in PHP that requires listing a big CSV file values ordered by string length.</p>
  <p>I'm currently using:</p>
  <pre><code>if (($process = fopen($CSV_file, &quot;r&quot;)) !== FALSE)
  {
      $CSV_array = array();
      while (($CSV_line = fgetcsv($process, &quot;;&quot;)) !== FALSE)
      {
          $CSV_array = array_merge($CSV_array,$CSV_line);
      }
      fclose($process);
  }
  
  usort($CSV_array, function($a,$b) {return mb_strlen($b) - mb_strlen($a);});
  </code></pre>
  <p>Xdebug tells me that <code>usort</code> is taking almost half the computing time of the whole program (not displayed here).</p>
  <p>Would you know any way to optimize that piece of code?</p>