[Brion Thompson]

Hi everybody!
I have successfully solved my performance problems with multiprocessing in After Effects CS5 on a Mac Pro by turning off hyperthreading.

I just started a new job as an After Effects artist for a company that does a lot of green screen work. To my pleasant surprise my boss set me up with a top of the line Mac Pro workstation, a 12 core 2.93GHz with 32GB of RAM and dual 24″ displays.

I was completely disappointed by the render performance with multiprocessing enabled. In some cases it was just stopping altogether. Even with RAM and processor cores dedicated to other applications I couldn’t even surf the web with a render in progress. Trying to use the multiprocessing brought the whole system to its knees. I did some research, adjusted settings in the multiprocessing preferences and tried over and over again to get the performance I knew this thing was capable of.

After some more research I finally found some information on how to disable hyperthreading on the processors.

I installed the bare bones xcode off the OS X install DVD with all the extra stuff turned off. After the install was complete I found the processor pref pane, double clicked on it to install it into my preferences and unchecked the hyperthreading checkbox.

After a quick restart I set up my multiprocessing preferences in After Effects.
Out of 32GB RAM total.
4GB Ram of other applications.
2CPUs reserved for other applications.
2GB RAM allocation per background CPU.

My next test render finished a project that took 31 minutes previously, in 1 minute 40 seconds. My RAM previews are very zippy as well. I know I was having a hard time finding any information on this. So I hope this comes in handy to somebody else out there.