Concat performance
<p>I was reading a <a href="http://blogs.msdn.com/b/wesdyer/archive/2007/03/23/all-about-iterators.aspx?PageIndex=2#comments" rel="nofollow">blog post</a> on msdn about iterators which talks about about how <code>Concat</code> has <code>O(m^2)</code> performance where <code>m</code> is the length of the first <code>IEnumerable</code>.  One of the comments, by richard_deeming on the second page, provides some sample code which he says is much faster.  I don't really understand why it's faster and was hoping someone could explain it to me.</p>

<p>Thanks.</p>
