blackmore90,
There is no notion of falling behind or not being able to process sweep data fast enough for the BB60C. For any given sweep there is a fixed amount of processing that needs to take place, the Atom processor will simply take a bit longer to do this compared to others, which means that in your sweep loop test code, more time is spent processing per sweep so you see the CPU usage increase.
The CPU usage numbers you are seeing look normal, as you are simply in a busy loop by telling the receiver to sweep as quickly as possible. If you wanted to reduce power consumption or reduce CPU load you could introduce a delay between each sweep. This would average out your CPU usage to a smaller number.
Let me know if you have additional questions.
Regards,
Andrew