I'm on windows but for me, anything over 50% rt CPU can be glitchy. By disabling master track plugins and freezing other tracks I can manage it well. Having fx on armed tracks really Jack's it up too.
https://forum.cockos.com/showpost.ph...84&postcount=3
The RT ("Real Time") CPU meter measures the amount of CPU time used by the audio thread servicing the sound device. Since it's measuring a single thread, it reflects only the CPU time used by one core, and gives you an indication of how much leeway you have in processing. If you have anticipative FX enabled (and few tracks record armed), RT CPU will generally be pretty low, as most things should be done asynchronously, allowing the realtime thread to quickly put things together.
-Justin