Expert question: Why is blitting slower in a usercontrol?

I'm using bitblt for some animation in my program:


Call BitBlt(picStocksBuffer.hdc, 0, i% * iRowHeight, 600, iRowHeight, mvarRowPicture(iIndex).hdc, 0, 0, SRCCOPY)


Basically, I'm copying the picture of mvarRowPicture(iIndex) to the picture of picStocksBuffer (which are both pictureboxes).

Now when I execute this code in an .ocx usercontrol (with the pictureboxes on the usercontrol) instead of my standard form, it is slower about TEN times ! (about 0.08sec instead of 0.009 on the standard form).

Anybody has an explanation for this ?

Thanks a lot,
Felix