Meters in the System Usage window indicate how much of your system’s processing power is being used when processing audio, and when writing and playing back automation.

As these meters approach their limits, host processing and recording or playback of automation data can be affected. If CPU Activity is high, a system error may occur. If Disk Activity is high, Pro Tools | First may miss playback of some automation data during particularly dense periods of activity, such as exporting the audio mix.