Hi Babu,
Take a look at this sample in windows\Grid.Windows\Samples\Performance\TraderGridTest to see if that helps in boosting performance.
There is another way you can freeze the painting. This technique works for any control and is discussed in one of our WIndows Forms FAQ. It adds aFreezePainting property to the class that you can turn on and off. This technque has worked in situations where BeginUpdate is being cancelled for special reasons. Here is a forum thread that has the references to the FAQ and includes a sample of how to use it.
Forum thread :
http://www.syncfusion.com/Support/Forums/message.aspx?MessageID=9290
Maybe this technique will work for you.
http://www.syncfusion.com/FAQ/WindowsForms/FAQ_c95c.aspx#q637qThanks,
Haneef