mainstage cracks and blips

1. What machine are you running, and what year is the model? e.g. iMac, MacBook, MacBook Pro, 13", 15" etc.
2. Are you running an audio interface or just the output from your Mac? If you have an interface, what is it and are the drivers up to date?
3. If you have an interface, have you tried changing the cable that connects it to your Mac?

From the very little info you've provided, I'd say that your interface/drivers are the issue OR you're running a 13" laptop (these tend to have issues when running MainStage)....but we need more info about your system to help you further.

Have you always had this problem? If it's something you've always experienced with your MacBook Pro 13" and MainStage I'd say it's due to the machine being the 13" model. They're renowned for struggling with MainStage and in particular, for the exact audio issues you've described....especially if the issues are occurring with both your external interface AND the Mac's internal audio. The 13" models are generally underpowered for MainStage's resource demands, although Apple's release notes for MainStage v3.3 say this has been improved. Regardless, I've seen this situation (online and in person) time and again. You'll find plenty of reports on this forum about it.

I suggest trying a completely different (and highly regarded) audio interface and if the same problem occurs, it's almost a certainty that your MacBook is the culprit. I've only used 17" and 15" (after the 17" was discontinued) MacBook Pro machines and have only once experienced something like you've described....and that was due to a low-quality FireWire cable. On the other hand, every single 13" MacBook Pro I've seen trying to run MainStage has suffered from audio crackles and CPU overloads with buffer settings of 128 and less, even from relatively "small" loads eg single Kontakt instruments. You could try a buffer setting of 256 but the latency would be pretty significant. Personally, I can't tolerate latency any greater than 64 samples.

Just a thought: have you disabled MultiCore processor support in Kontakt? That option shouldn't be enabled when using Kontakt as a MainStage plugin.

Something else to check: do you have the same issues if you run Kontakt as a standalone app? If you don't have the problems when running Kontakt as a standalone, that's another sign that your MacBook and MainStage just aren't going to work together.

Finally, try the demo of the "GigPerformer" application....there are a bunch of positive reviews by guys who had issues with MainStage but found that GigPerformer worked great for them.

Live is MUCH more efficient than MainStage....you can't compare their performance.

I've told you before (and from much experience): MainStage does NOT run well on 13" machines but I guess you'll need to come to that conclusion yourself.

What are your buffer settings?

Good luck with that.