I've found that the roOneLineDialog seems to eat up a lot resources while it's running, particularly if showing the busy animation. The following example illustrates this very well...

dialog = CreateObject( "roOneLineDialog" )
dialog.ShowBusyAnimation()
dialog.SetTitle( "Please wait..." )
dialog.Show()
' do initialization stuff
keyboard = CreateObject( "roKeyboardScreen" )
keyboard.SetMessagePort( CreateObject( "roMessagePort" ) )
keyboard.AddButton( 0, "OK" )
keyboard.Show()
While true
    msg = wait( 0, keyboard.GetMessagePort )
    If msg.IsButtonPressed() Then
        Return
    End If
End While

When you run the above code, you'll find that the cursor is extremely sluggish when moving around the keyboard. The obvious solution is to Close() the dialog before entering the while loop, but all other screens seem to stop processing when they lose focus, while the dialog doesn't. I have some screens in my app that take a few seconds to paint, so closing the dialog before the screen paints isn't very smooth from a UI perspective. I've gotten around it by passing the dialog to my custom screen, so it can close it before entering its wait loop, but I'm curious as to why it behaves the way it does.

TheEndless