title: Consider marking event handler as 'passive' to make the page more responsive
body: <p>I am using hammer for dragging and it is getting choppy when loading other stuff, as this warning message is telling me.</p>
  
  <blockquote>
    <p>Handling of 'touchstart' input event was delayed for X ms due to
    main thread being busy. Consider marking event handler as 'passive' to
    make the page more responsive.</p>
  </blockquote>
  
  <p>So I tried to add 'passive' to the listener like so</p>
  
  <pre><code>Hammer(element[0]).on("touchstart", function(ev) {
    // stuff
  }, {
    passive: true
  });
  </code></pre>
  
  <p>but I'm still getting this warning.</p>