title: Performance impact of unused "using" directives in C#
body: <p>Just curious about it.</p>
  
  <p>Does it matter if I add multiple <code>using</code> directives at the starting of my code file which I don't use in my code. Like this.</p>
  
  <pre><code>using System;
  using System.Web.UI;
  using System.Web.UI.WebControls;
  using System.Data;
  using System.IO;
  //using blah.. blah.. blah..;
  
  public class myClass
  {
      // Class members
  }
  </code></pre>
  
  <ul>
  <li><p>Does it have a bad impact on my application's <strong>memory usage</strong>? </p></li>
  <li><p>Does it have a bad impact on my application's <strong>performance</strong>?</p></li>
  </ul>
  
  <p>I know it is a good practice to remove them and we have short full support of .Net IDE to do so, but I am just curious to know about it.</p>