title: String Interpolation vs String.Format
body: <p>Is there a noticable performance difference between using string interpolation:</p>
  
  <pre><code>myString += $"{x:x2}";
  </code></pre>
  
  <p>vs String.Format()?</p>
  
  <pre><code>myString += String.Format("{0:x2}", x);
  </code></pre>
  
  <p>I am only asking because Resharper is prompting the fix, and I have been fooled before.</p>