title: Most performant way of checking empty strings in C#
body: <p>What is the best way for <strong>checking empty</strong> strings (I'm not <a href="https://stackoverflow.com/questions/263191/in-c-should-i-use-string-empty-or-string-empty-or">asking about initializing!</a>) in C# when considering <strong>code performance</strong>?(see code below)</p>
  
  <pre><code>string a;
  
  // some code here.......
  
  
  if(a == string.Empty)
  </code></pre>
  
  <p>or</p>
  
  <pre><code>if(string.IsNullOrEmpty(a))
  </code></pre>
  
  <p>or</p>
  
  <pre><code>if(a == "")
  </code></pre>
  
  <p>any help would be appreciated. :)</p>