title: What is the trade-off for disabling CSS in HTMLUnit?
body: <p>I experienced slowness in HTMLUnit 2.12, and therefore disabled CSS as explained in
  <a href="https://stackoverflow.com/questions/10442803/htmlunit-super-slow-execution">HTMLUnit : super slow execution?</a>.</p>
  
  <p>I want to understand what the trade-off is.  Does it mean that I cannot use XPath selectors? Are there other tradeoffs?</p>