Hi, I just tried running all of the mason demo programs under Leopard on a 2Ghz Intel Core Duo MacBook pro. They all ran and seemed okay but that's not saying much since it had been awhile since I ran the demos. The 3D Particles ran the slowest and took a while to initialize. I'm conducting some speed test on my model (non-graphical) over the next couple of days and will report the results and will be able to compare to 10.4 on the same computer since I have a 10.4 install on an external hard drive. Mark On Oct 31, 2007, at 12:56 AM, Sean Luke wrote: You've probably heard: OS X 10.5 (Leopard) runs Java exceptionally slowly if at all. This is because they've turned off OpenGL hardware acceleration (or what little of it they had in 10.4). I've been told that a number of Java simulation environments, such as Processing, are having difficulty. I have not tested MASON under Leopard and cannot verify that it will run well or not. But given Leopard's serious Java problems, you may wish delaying any upgrade until a later version (10.5.1, perhaps). Sean