Responsiveness of UI controls becomes very slow when the window size is very large, and a MediaPlayer is playing at the same time.
When I hover over the play controls, (eg. play, pause, stop, back), it takes a long time for the hover icon to display, when the MediaPlayer is playing.
And it also takes a long time for the action to take effect, when the MediaPlayer is playing (see test/PlayerTest.java).
On a 2.4 GHz Core2 Duo processor with an NVidia graphics card, it takes between 2 and 10 seconds for the hover icon to update when the MediaPlayer is playing,
when the window size is very large.
If the window size is set to be smaller, the responsiveness of the UI controls is better, even if the MediaPlayer is playing at the same time (see test/DesktopTest.java).
As an example, look at apps/internal/EmbeddedMediaPlayer, and run the main methods in test/DesktopTest.java and test/PlayerTest.java

When testing, the movie file that is referenced is outside the Oracle firewall.
So proxy settings will be required to view the movie file from inside the Oracle firewall.