If you have an audio issue with your Mac that happens in any MainStage concert or Ableton set and you've already addressed possible CPU issues here, it might have to do with your Macbook Pro. You'll want to test with a couple different audio interfaces and see if that makes a difference to rule out issues with your audio interface in particular. If you are using the most recent Mac OS there are times where you need to update drivers or firmware to use another product with your Mac.
Some users have reported an issue with with Apple's T2 chip which involves an overload of a USB bus running in the slower USB 2.0 speed. The only permanent fix if this is the issue it to use a thunderbolt dock (not USB), which are quite pricey. Apple supposedly patched the issue in Mojave 10.4.4 but seems like there are still reports of it happening even on Catalina. This article covers the issue and a method that can help reduce the issue: https://appleinsider.com/articles/19/02/19/pro-audio-glitch-with-t2-equipped-macs-connected-to-usb-20-connections It involves turning off the “Set Date and Time Automatically” in System Preferences.
You can also review our video about CPU optimization here: