title: Determine if an IEnumerable<T> contains any object of another IEnumerable<T>
body: <p>I have 2 <code>IEnumerable&lt;int&gt;</code></p>
  
  <pre><code>IEnumerable&lt;int&gt; x;
  IEnumerable&lt;int&gt; y;
  </code></pre>
  
  <p>What is the best best way to determine if any int in y is present in the x?<br>
  Currently I'm using:</p>
  
  <pre><code>return x.Intersect&lt;int&gt;(y).Count() &gt; 0;
  </code></pre>
  
  <p>Would it be significantly faster to loop through and test each individually?</p>
  
  <pre><code>foreach (int i in x)
  {
      foreach (int j in y)
      {
          if (i == j) return true;
      }
  }
  return false;
  </code></pre>
  
  <p>The lists are relatively light, with not more than 50 ints in x and 4 in y if that matters in the consideration.</p>