Note that in all of Mathematica 8, 9, and 10, the example (without the TrackedSymbols option) is constantly running the Kernel. This is usually an indication that the code needs to be reviewed to determine what the Manipulate is in a constant evaluation loop with. So, I would look to this issue first in modifying your examples (if indeed they all have this behavior which is exhibited by the example).

I found TrackedSymbols, too, long after DR. For me (Windows and Mac) with 10.0.1, the hands still don't move as smoothly as with 9.

It may be a case where the code needs to be pulled out of the Manipulate and timed to see what slowed down. In my court, but I won't object if someone wants to try it and report back.

I will take a look at this some more later on... but one thing that I noticed at first when executing your Manipulate code in a separate notebook (both on version 9 and 10) is that the cell bracket is always hi-lighted, indicating that the Kernel is constantly updating your Manipulate even though it is not being interacted with. This is fixed, I believe in this particular case, by adding a TrackedSymbols option for the variables that you are changing:

TrackedSymbols -> {\[Theta], a, b, c, vs}

See if this makes a difference to your example and let me know.

By the way, I really like the design of your visualization....

Perhaps provide an example or two? It is very hard to debug something without a test case.