How intense is the demo? Can you give some sample links?
As I understand it, as of mixed mode, if nothing is moving, CPU (for that app) should be near 0 - assuming the demo is well designed.
For a clear reading, you should probably only have 1 window / 1 tab open, and then the CPU / GPU usage in the chrome task manager (shift-esc). This is on OSX, right? What version of Chrome? And you say this is on all your browsers, which others?
Note that things like having a transparent window from some other program over your browser window can affect rendering.
Also, assuming this is for pure famous demos, it's probably better to report this upstream. I'm not an expert on famous' internals, unfortunately. But the info I asked for here will probably help them a lot :>
Re the link; yeah, these are all the kinds of principles famous adopts. There are a few crucial links in there to very NB info, but, a lot of that stuff famous handles for you so you don't have to. Not everything though and some useful stuff to keep in mind; a few things are mentioned at http://famous.org/learn/pitfalls.html.