Anyway it seems that you can’t get the “multiple pixels packed into an int” idea to work with an IndexColorModel, which is unfortunately what I am using.
Silly suggestion, but are you running these tests on the server VM?
[quote]Silly suggestion, but are you running these tests on the server VM?
[/quote]
I’m testing the performance on the client VM because as far as I know, there doesn’t seem to be a way to run the app with the server VM via webstart… or is there?
Even if there is (i don’t think there is a non hackish one), you can be 99.99% sure the user is running your game on the client.
Unless you, ahh, ship a JRE embedded in the game with the server VM 
Cas 
From 1.5 webstart supports arbitrary VM arguments which ought to include -server. No doubt it will only work if the selected JRE has the server VM installed, but perhaps you could have an installable extension which contained the server VM dll and copied it to the right place in the chosen JRE. Obviously the .jar file would have to be signed, but it looks feasible.
-server is listed as supported here
http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/syntax.html
To assist in adding the server JVM, the ExtensionInstallerService stuff looks ideal.
It would be really helpful if Sun would wrap up the server JVM as an extension JNLP and host it somewhere.