_From some of your questions, I gather that you are using
Java2D (DisplayImplJ2D) rather than Java3D (DisplayImplJ3D).
I recommend Java3D, even for purely 2-D graphics. It has
better performance for user interactions, including 2-D
panning and zooming. Much better in some cases. Furthermore,
Java3D's texture mapping provides a reasonable way to render
images remapped to non-rectangles, where Java2D does not
(DisplayImplJ2D emulates texture mapping as lots of little
triangles, with miserable performance).
Good 3-D graphics are becoming so cheap and ubiquitous
that there is really no reason not to use them, even for
2-D graphics. This is especially true for projects like
yours aimed at 2007 and beyond.