First of all my problem is not directly related with wingrid 's performance but overall painting 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. How can i get rid of this flickering ?

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

Regards.