When you make a IFF image, check the colour depth of the image. Less colours = Faster loading and smaller file size... And these colours can be made to match those supported by a low colour WB by using some special modes in Paint Shop Pro 6.
Also, dont make the image any larger than what you can see on the screen. It'll just mean your system has to load more image for no reason.
I did some tests on this and found that, say you've set 640x480, then the title bar shifts the image by 11 pixels downwards, cutting off the bottom 11 pixels of the image, so the image should be 640x469 for optimium performance.
Hope this is of some use... (I figured you might be doing some image editing at some stage...)
Hodgkinson.