title: WPF Datagrid Slow Performance
body: <p>I'va a problem with Datagrid performance where I grouped my ObservableCollection.
  There are about 3500 items in my datagrid, and the display is very very long... (about 1 min).
  I've tried without the GroupDescriptions and it works fine.</p>
  
  <p>So, after researches, I've tried to set EnableColumnVirtualization and EnableRowVirtualization to True and realiez my binding asynchronous (IsAsync = True) without result.</p>
  
  <p>Do you have any ideas to help me ?
  Thanks </p>