Issues with performance and RAM previews

Question

Just did a major system upgrade from an iMac to a Mac Pro, and now I'm having an issue with performance...specifically with RAM previews.
When I try to do a RAM preview with audio, it grinds my entire OS to a hault (can't switch apps, or click on much of anything). It eventually clears up enough for me to stop the RAM preview.
So, I'm wondering if maybe my Memory & Multiprocessing settings might be off.
Here are my system specs:
Mac Pro
2 x 2.4GHz 6-Core Intel Xeon (12 cores)
64GB RAM
ATI Radeon HD 5870
AE CS6 (11.0.2.11)
AE is installed on an SSD drive and the scratch disk is an internal HDD.
Here are my AE Memory Settings:
Here's my GPU Info:
Let me know if any other info is needed...   

Answer 1

You are reserving far too little RAM for other software.
See this: "Performance tip: Don't starve your software of RAM."
(Also, I recommend going through all of these materials: http://forums.adobe.com/thread/543440 )
Regarding the SSD: Putting your application files on it means that applications load/boot faster. This is fine, but that benefit is just when you first start the application. If you put your cache files on it, then you get the benefit every time that something is read from or written to the cache---i.e., many times per second, for the entire time that you're working. Put your cache files on your SSD. BTW, there's no reason to not put your application files and caches on the same SSD. The reason that you split things across multiple disks is to prevent simultaneous reads and writes to and from a slow disk; the program loading from disk happens at a different time than reading and writing cache files, so there is no potential for conflict and slowdown.