title: Efficiency: switch statements over if statements
body: <p><a href="http://pmd.sourceforge.net/pmd-5.0.0/"><code>PMD</code></a> tells me</p>
  
  <blockquote>
    <p>A switch with less than 3 branches is inefficient, use a if statement
    instead.</p>
  </blockquote>
  
  <p>Why is that? Why 3? How do they define efficiency?</p>