title: Delay after prepareForSegue before UIStoryboardSegue/View shows up
body: <p>I have a simple iOS application written in Swift that is hanging every 2nd time I tap a row to present the next view.</p>
  
  <p>The first time, 3rd, 5th, etc times I select a row it waits for 5-15 seconds and then a modal <code>MZFormSheetPresentationController</code> (or whatever modal view) is shown. </p>
  
  <p>If I dismiss and tap the row again (to show the same modal) it appears immediately. If I'm in the delay sequence and I tap somewhere else it triggers the appearance immediately. That made me feel like a main thread issue, but I can't find anywhere I get off track.</p>
  
  <p>I found <code>prepareForSegue</code> was missing a super call, but adding it, or commenting entirely has no bearing. Happens regardless of if the Segue kind is Modal or Custom; if it has a custom class or not, if animates is enabled</p>
  
  <p>Sometimes it feels like taps are being dropped entirely (The dismiss button feels especially random).</p>