I had been having problems with very glithchy, sluggish graphics performance in Logic 9 for the last 6 weeks, after upgrading from OS 10.6 to OS 10.8. I searched through all of the message boards, tried a few different tricks and even called Apple support. Nothing worked. I finally "gave up" and upgraded to OS 10.9.1 Mavericks. The results were even worse! And, My call to Apple support was a waste of time. All they did was refer me to the Logic troubleshooting webpage. I was really disappointed to discover that OS 10 Mavericks performed so poorly. Fortunately I had cloned my previous system drive and so still had a fully bootable Snow Leopard system with Logic and all of my software instruments and effects plugins on stand-by. I had started this whole upgrade process so that I could be "compliant" with NI Komplete 9 Ultimate's system requirements. While doing all of this forum searching, I had noticed that some users had installed Komplete 9 on Snow Leopard systems and had no problems. SO THAT'S WHAT I DID! I re-intalled all of my latest sofware puchases including Komplete 9 Ultimate to my Snow Leopard clone drive. (Internal HD on a Mac Pro 8 core 2.26). EVERYTHING WORKS in Komplete 9 Ultimate on my Snow Leopard system! (Individual results may vary by hardware configurathion) I went from having an unusable OS 10.9 Logic system to having a SMOOTH AS GLASS, OS 10.6 Snow Leopard Logic system, that now has all the software I will ever really need! I cannot stress how important it is to BACK UP your old system drive! I used Carbon Copy Cloner. A stellar product. Thank you Mac Pro Video for continually stressing the importance of backing up data before major upgrades. Keep up the GREAT WORK! Your advice helped save my whole studio set-up! Thanks and Cheers! Rob

Hey Rob, Thanks for the post! Glad to know you've found a system that works better for you with LP9 and Komplete 9. I haven't personally upgraded to Mavericks yet, but when I do I'll be backing up a couple of times before hand. Also agree: Carbon Copy Cloner is an amazing product... essential IMHO. :)