sjc

Dick, I too am suffering these exact issues after reluctantly upgrading 10.6.8.to 10.8.5, like you purely for new software! CPU spikes and lowsy performance now. Its a joke. 10.8. seems to be a very CPU hungry OS. I will be going back down to 10.6.8. I should have known better!

I'm having EXACTLY the same issue in Logic Pro 9.1.8. Having worked flawlessly on 10.6.8 for years with no CPU issues, I reluctantly went to 10.8.5 needing new Plugs that were uncompatible with the older OS, thats when it all went wrong. CPU spikes and clicks in projects that otherwise ran before. Sluggish performance. Mac Pro 18Gb Ram 2x 2.4 Ghz Quad Core (so plenty of grunt). Tried increasing Logic buffer to maximum and large process buffer range but to no avail. It seems 10.6.8 was a less hungry OS?? Are you aware of anything else that might be causing this problem?? I even went up to Mavericks in the hope it might miraculously improve but the problem persists. I will be watching WIFI today to see if this is the culprit. So Frustrating..