This is reproducible with the latest mustang build on JDS-cinnabar system.

Painting is slow on SplashScreen. After moving a window over the SplashScreen, the obscured portion of the SplashScreen is repainted quite slowly. This gives the impression that the application is hanging. I've observed it only on cinnabar systems - behaves fine on Solaris and Windows.

To reproduce, run the attached testcase with -splash option. The behavior is quite obvious with a bigger size splash screen image. The testcase sleeps for 20 seconds and then shows a Frame. While the SplashScreen is visible, move a window over the splash screen repeatedly. It could be seen that the frame does not come up even after 20 seconds. It takes much longer time - depending on how often the SplashScreen was repainted.

Also attached is the thread dump, after 20 seconds.