Didn't see this in any of the dicussions.....I've the same problem that started when I
--Upgraded the OS.
Purchased a MPB/ Logic 9.16 in Dec. 2011. Plenty of CPU power/ especially for NI VI's. I updated the OS (checked all other updates) and suddenly just one instance of Reaktor/Prism or Spark caused CPU overloads (no audio tracks..just a few VI's). I searched several Apple forums/threads and OSX's power management allows the CPU to 'runaway' and use 600% of the processor, forcing you to 'quit' out of the current task and wait for the processor to cool down (a 'feature' that is supposed to extend the processor's life) . There are dozens of threads and complaints about this , with moderators/experts status contributors recommending "Resetting the Power Management System". One post recommend removing the power management .kxt file(its buried in the library, each model has its own profile). Though I' don't ever recommend messing with the OS, I was beyond frustration. This allowed for extended periods of use (more like a band-aid), but not a solution.
---Old school solution finally worked! …
Opened up the computer and blew out the dust on the cooling fins with compressed air. Good as new! These CPU's run hot and cost/design doesn't seem to allow any wiggle room regrading thermal issues. I need to do this every 2-3 months as I have a dusty environment. Only saw one posting on this recommendation. I've seen all sorts of wacky solutions on YouTube from unplugging an external Thunderbolt monitor, headphones, putting the computer to sleep.
--Run your Activity Monitor in the background next time- Applications>Utilities>Activity Monitor to see if the "kernel task" is bogging down the system. I also encountered this when watching a streamed video off Netflix, audio/video out of sync, jittery. Checked the Activity Monitor, same issue. See attached screenshot
Attached, the dusty cooling fins and the system idle (No apps running). 2014 and we still have to do workarounds...