Copying an image into Swing's default back buffer using alpha compositing
is way slower than it was in jdk1.3.1. The same is true for copies into
any VolatileImage (such as Swing uses for its back buffer).
Run the attached AutoTest app. Click on the overlay (translucent) image and
drag it around the screen. On jdk1.3.1, you should see farily snappy
performanc. On jdk1.4, however, you will notice very choppy behavior as each
frame of the animated dragging takes a long time to render.
This is also a problem with the new XP look and feel work in Swing. Due to the
many translucent components in this look&feel, we end up punting the Swing
back buffer and then get poor performance for other opaque images
that still exist in VRAM.