Getting previews/screenshots of all open windows

[ade low]

I am experimenting with the idea of creating my own program that gets previews/screenshots of all open windows. At the moment, it does this by iterating through all open windows and getting the screenshot using gdk_pixbuf_get_from_drawable and then scaling it using gdk_pixbuf_scale_simple.

Is there a more CPU-efficient way to do both of these things, without using 3D acceleration?