title: Parse markdown on the fly
body: <p><strong>I want to implement markdown to my forums.</strong></p>
  
  <p>I research many possible approaches how I would do that and this is what I thought:</p>
  
  <p>A simple approach would involve pagedown on client side and php-markdown on the server.</p>
  
  <p>My approach is to save pure markdown to database and when displaying convert to HTML (with pagedown). Since I already have security layer for my server side (HTML elements whitelist) and all the necessary staff I don't see anything to lose here.</p>
  
  <p>What I win in this case? well I have to modify pagedown to use custom buttons and patterns. That would be hard for me to maintain both php and JavaScript.</p>
  
  <p>My question is: is this good aproach?
  To break this question:  </p>
  
  <ol>
  <li>Is there any serious overhead on client side loading about 30
  posts and converting it to HTML (performance)</li>
  <li>With the Idea that I check elements whitelist, is there any
  security issue I need to know about? (Security)</li>
  </ol>