Audio issues that you don't expect are usually due to CPU performance.
We have some tips and tricks on optimizing your CPU performance in this video:
There is currently a bug in MainStage that causes popping or cracking types of sounds to occur when using the built-in output as the audio output device in MainStage. This only seems to occur on some systems, and a current solution is to use an audio interface as the output device.
An audio interface will also take strain off your computer. Generally the sound does not get “better” by using an audio interface- but audio interfaces are handy for allowing you to send multiple outputs easily. Audio interfaces will generally give you more headroom with the sound as well, and you are able to push out my audio signal at a much louder level- without running into any noise floor issues. Technically an audio interface will allow you to output your sound at a higher sample rate if desired- but we highly recommend the standard 44.1kHz as it plays the nicest with your CPU and you won’t notice the difference in a live setting. It also gives you a large output knob for your entire rig.