See attach file for sample project :
http://www.mikrokom.com/downloads/performance.zip

First of all my problem is not directly related with wingrid 's
performance but overall painting performance and transparency problem.
I have a sample project. There is an mdi main form, an mdi client in
it. There is a button over this mdi client which is opening a new
dialog form. There are bunch of controls over this form. Groupbox,
toolbar, labels, textboxes etc.
When that dialog form is opening painting is very slow.
Please download attachment and run the project and you 'll see what i
'm talking about. To improve paiting performance there is a code :

protected override CreateParams CreateParams
{
get
{
CreateParams cp = base.CreateParams;
cp.ExStyle |= 0x02000000;
return cp;
}
}

see frmDialog.cs , uncomment required lines and run project. This time
you 'll see significiant performance improvements. Unbelievable.
But the problem here is there is a flickering problem on toolbar. A
black line appearing when form is loading and then disappears. This is
annoying.

For more information about this issue please see
Flicker-free painting
http://social.msdn.microsoft.com/Forums/en-US/winforms/thread/aaed00ce-4bc9-424e-8c05-c30213171c2c

I am using Windows XP service pack 3.
Infragistics components are
7.3.20073.1043

I've recorded screencapture. Both videos are about 1.5 mb quicktime
movie.

in normal case , without using WS_EX_COMPOSITED painting is extremely
slow. Here is the video link :

http://www.mikrokom.com/downloads/NORMAL.mov

and if you work with WS_EX_COMPOSITED code you can see painting is
very acceptable - at least not one by one - but you see a black area
between second 5 'th and second 6 'th of the video.

here is the other video link :
http://www.mikrokom.com/downloads/WS_EX_COMPOSITED.mov

How can i get rid of that black area in place of toolbars.

I tried this with the latest (last) 7.3 build on Vista and I really didn't see a noticeable difference; I definitely did not see a "...black line appearing when form is loading...". MSDN documentation for the WS_EX_COMPOSITED constant states:

"Paints all descendants of a window in bottom-to-top painting order using double-buffering."

The toolbars appear in docked panels on the form, so I don't know if possibly changing their z-order might affect this.