Hello Shengjie,

I have been investigating your issue and found out that the implementation of the SimpleTextBox inside the XamTextEditor was needed to improve performance on the XamDataGrid. After trying a few things I think your best option would be to revert to using a TextBlock in the XamTextEditor. You can do this by altering a copy of the original template’s Template property setter for the XamTextEditor. You can find it the EditorsGeneric_Express.xaml (here is default installation path: C:\Program Files (x86)\Infragistics\NetAdvantage 2010.3\WPF\DefaultStyles\Editors). All you have to do is switch the SimpleTextBlock with the previously used element which is actually preserved in the part from the ControlTemplate  I have plucked from the above mentioned file:

<!-- MD 8/12/10 - TFS26592 - Use the SimpleTextBlock instead -->

                        <!--<TextBlock x:Name="TextBlock"-->

                        <igwindows:SimpleTextBlock x:Name="TextBlock" …

Please let me know if you require any further assistance on the matter.