title: Merge two Lists of different types
body: <p>I add data to the objects of a List from another List:</p>
  
  <pre><code>public void MergeLsts(List&lt;A&gt; lstA, List&lt;B&gt; lstB)
  {
      foreach (A dataA in lstA)
      {
          foreach (B dataB in lstB)
          {
              if (dataA.ItemNo == dataB.ItemNo)
              {
                  //dataA.ItemDescription is up to this point empty!
                  dataA.ItemDescription = dataB.ItemDescription;
              }
          }
      }
      DoSomethingWithTheNewLst(lstA);
  }
  </code></pre>
  
  <p>This works perfectly fine. However it takes pretty long because both lists get quite large (around 70k items in lstA and 20k items in lstB).</p>
  
  <p>I was wondering if there is a faster or more efficient way to accomplish what I need? Maybe with LINQ?</p>