Interactive MPEG4 authoring - more notes

My article on Interactive MPEG4 Authoring using XMT appeared last week on streamingmedia.com and is getting a lot of traffic.  One thing I've learned from readers is that the interactive MPEG4 example and source code that goes with the article requires a lot of CPU horsepower to play.  Users on 450MHz Pentium systems get choppy, halting playback, and I've confirmed this using my old dual-processor Pentium 300MHz machine.  On my 800MHz machines, the example, which is encoded at about 516kbps, plays just fine. 

I'm not sure if it's the IBM M4Play applet I'm using that's got high CPU needs or if any MPEG4 player that supports this profile would be the same.  Since the QT and RealONE players don't play this content, I haven't been able to easily check it out.