The choppiness is an issue with the default Power Profiles, which say that when running off of battery power, underclock a bunch of stuff and start turning off unnecissary components when not in use (like hard disk when not accessed, DVD drive when there is nothing in it, etc.)
The problem there is that it takes a moment for EFI to realize that "oh, I am starting to use a ton of resources, I better go back up to the normal clock speed."
When doing something like opening Photoshop or starting to do a video project, this should not be seen, but when doing something like a quick CoreImage effect like you see on Expose or Dashboard, then you run into a problem as it can not get the resources up fast enough.
There has been some talk in the Apple Forums that in the mean time, you can resolve the issue by going into System Preferences -> Energy Saver -> Battery and turn off "Put Hard Disk(s) to sleep when possible" and set Optimization to "Performance". Apparently, this is also going to be addressed in the next OS Update.
No info on how they are going to fix it, but as a developer myself, what I would do when calling Expose or any other CoreAnimation program, I would first make a call to EFI returning the clockspeeds to their default settings and then run it rather than just rely on EFI trying to think for me... But then, to each his own.
