From http://blogs.msdn.com/b/oldnewthing/archive/2007/07/18/3926581.aspx:
[quote:2bzq6b3g]The first answer is "If you have to ask, you're probably doing something wrong." Programs shouldn't be creating anywhere near ten thousands window manager objects in the first place.
Along the same lines: I don't understand how you could possibly need so many thousands of individual images? What are you doing? Surely there is a better way?
The editor could spritesheet images for preview, but that would be a big architectural change and could slow down preview. And I don't see the point, since needing thousands and thousands of images does sound like you're doing something wrong.