title: Using a private class in place of a field - performance/memory penalty?
body: <p>I'm reviewing someone's code and came across this private class:</p>
  
  <pre><code>class CustomType : Dictionary&lt;int, SomeOtherCustomType&gt;
  {
      // This is empty; nothing omitted here
  }
  </code></pre>
  
  <p>CustomType is then used all over the parent class. This is neat of course, since CustomType is shorter than</p>
  
  <pre><code>Dictionary&lt;int, SomeOtherCustomType&gt;
  </code></pre>
  
  <p>My question is, what are the performance/memory implications of having an inner class just for a shortcut? In a performance sensitive application, does this contribute (even slightly) to higher memory and/or CPU usage?</p>