title: Linq with DataTable .ToList() very slow
body: <p>facts.UnderlyingDataTable is a DataTable</p>
  
  <hr>
  
  <pre><code>var queryResults4 = //get all facts
      (from f in facts.UnderlyingDataTable.AsEnumerable()
          where f.RowState != DataRowState.Deleted &amp;&amp;
              FactIDsToSelect.Contains(f.Field&lt;int&gt;("FactID"))
          select f);
  
  var queryResults5 = (from f in queryResults4.AsEnumerable()
      orderby UF.Rnd.Next()
      select f);
  
  
  return queryResults5.ToList();
  </code></pre>
  
  <p>The problem is this line <code>queryResults5.ToList();</code></p>
  
  <p>It returns a list of DataRows. But is super slow to do this. </p>
  
  <p>I am happy to return any object that implements <code>IEnumerable</code>. What should I do? I seems the conversion from whatever the var is to <code>List&lt;DataRow&gt;</code> is slow. </p>
  
  <p>Thanks for your time.</p>