The CPU meter doesn't necessarily show how much CPU Studio One is using, but how busy your CPU is and the impact it can have on S1's performance.
If you have high CPU activity when opening an empty song in S1, with no plugins loaded, I'd say there is something fishy going on with your processes.
Have you tried using Activity Monitor.app and sort the column on CPU & CPU Time?
This will often give the best indication of what applications and processes that actually drains your CPU(s).
Choose "View -> All Processes Hierarchically" in the menu bar, to get a good overview.
Sometimes the ucdeamon process fires up and uses a good deal of cpu power for some reason.
When this happens, I just open a Terminal and kill / sighup the process using:
$> sudo kill -HUP <PID OF PROCESS HERE>
And it calms down again...