title: ViewController transition bottleneck in UITabBarController
body: <p>When I tap on a specific UITabBarItem to switch ViewControllers, the transition takes about 4 - 5s.</p>
  
  <p>There is no heavy processing being done, so this leads me to believe that the code is simply inefficient.</p>
  
  <p>After having taken a look inside Instruments as suggested in the comments, I have pinpointed the following process to be taking ~> 2500 ms</p>
  
  <pre><code>Running Time    Self (ms)       Symbol Name
  2485.0ms   44.3%    0.0     
  TDescriptorSource::CopyDescriptorsForRequestFromArray(__CFArray const*, __CFDictionary const*, CFComparisonResult (*)(void const*, void const*, void*), void*, unsigned long, bool) const
  </code></pre>
  
  <p>and </p>
  
  <pre><code>Running Time    Self (ms)       Symbol Name
  3070.0ms   54.7%    0.0      -[UIStackView initWithCoder:]
  </code></pre>
  
  <p>What does this mean? </p>