title: Linq contains for compairing two huge list takes long time
body: <p>When i want to compare a huge list (about 700,000 elements) with a specific property and list of string, takes long time.</p>
  
  <p>I tried AsParallel but it doesn't help me any more. i need list for removedSuccessFromList because i want to use this list for start a Parallel.Foreach</p>
  
  <pre><code>List&lt;string&gt; successStrings = service.GetProperty().Select(q =&gt; 
  q.IdString).ToList();
  
  List&lt;Property&gt; removedSuccessFromList = properties.AsParallel().Where(q =&gt; 
  !successStrings.Contains(q.IdString)).ToList();
  </code></pre>