The CPU usage meter in Pro Tools LE indicates the percentage of overall CPU time being used by the Pro Tools LE audio processing engine (including RTAS plug-ins). It does not indicate the CPU usage of Pro Tools LE as a whole.Changing the CPU usage limit (i.e. from 65% to 75%) does not change the value displayed in the meter. Adding more plug-ins does, because this actually increases the CPU load. The CPU usage limit tells Pro Tools LE what the maximum engine CPU load is allowed to be before the -9128 error message is displayed .CPU meters in other programs (i.e. your Ontrack utilities) commonly base their calculations on the amount of time spent NOT executing the threads of any particular program (i.e. time spent in the system "idle" thread). This sort of calculation can be misleading because many programs (Pro Tools LE, for instance) spend otherwise unused CPU time performing regular housekeeping tasks. The fact that some CPU meter displays a high value (90% - 100%) does not necessarily mean that Pro Tools LE needs that much CPU time to function correctly.