on our quiz pages clicking through the pages, just stops and hangs for ages, i am testing on an old pc

here is the page:
http://www.avert.org/sex-quiz.php

here is the code

Code:
<script language="JavaScript" type="text/javascript" src="applications/quiz_app/js/jquery.js"></script>
<script language="JavaScript" type="text/javascript" src="applications/quiz_app/js/quizzes.js"></script>
<link rel='stylesheet' type='text/css' media='screen' href='/applications/quiz_app/css/online-quiz.css' />

<script language="JavaScript" type="text/javascript">
    
    jQuery(document).ready(function(){
        code = '<div id="quiz_container" class="quiz_step_select_level">';
        code += '<div class="quiz_h1_ie_hack"><h1>Sex Quiz</h1></div>';
        code += '<div id="quiz_level_picker">';
        code += '<div class="quiz_h2_ie_hack"><h2>please pick a quiz level</h2></div>';
        code += '<ul>';
        code += '    <li><button type="submit" onclick="startQuiz(\'23\', \'1\');" id="easy" value="1" name="rating" class="mediumBt"><span>easy</span></button></li>';
        code += '    <li><button type="submit" onclick="startQuiz(\'23\', \'2\');" id="medium" value="2" name="rating" class="mediumBt"><span>medium</span></button></li>';
        code += '    <li><button type="submit" onclick="startQuiz(\'23\', \'3\');" id="hard" value="3" name="rating" class="mediumBt"><span>hard</span></button></li>';
        code += '</ul>';
        code += '</div><!-- end quiz_level_picker -->';
        code += '</div><!-- end quiz_step_select_level -->';
        
        jQuery('#content').append(code);
    
    })    
    
</script>

<noscript>
<div id="quiz_noscript">

  <h1>Sex Quiz</h1>
  <div class="quiz_noscript_intro">
  <p>Sorry, Javascript needs to be enabled for this quiz to be played online. You can enable Javascript, or <a href="media/pdf_quizzes/sex_quiz.pdf">download the printable version</a>.</p>
  </div>
  <div id="quiz_noscript_center">

  <img src="media/layout/QuizLinksTop.gif" />
  <div id="quiz_noscript_box">
  <div class="links">
   <h2>Printable version</h2>
   <ul>
    <li><a href="media/pdf_quizzes/sex_quiz.pdf">Sex Quiz</a></li>
   </ul>
  </div>

 </div>
<img src="media/layout/QuizLinksBottom.gif" />
</div>
</div>
</noscript>
 

  
        </div>