After Effects not utilizing all cores

Question

I have a Z800 dual quad core machine and I turned hyperthreading on, so 16 virtual cores.  When running AE, I just applied a simple blur to a 24P timeline from a Pansonic HMC150 1080P/24 mode.  I only performed a simple blur effect and when I do a RAM preview only 13th core is really being used, all the others are practically dormant and it only utilizes an average of 10% of all processing power.  I have turned render simultaneous frames on and off using a variety of settings, but it doesn't matter.  It is Windows 7 64 bit and my machine has 36GB of RAM and running the Quadro FX 3800.  Using all defaults right now.

Answer 1

BTW, don't confuse multi-threading with the multiprocessing that is done by the Render Multiple Frames Simultaneously multiprocessing feature.
The Render Multiple Frames Simultaneously multiprocessing feature starts a separate instance of the After Effects application for each processor core, and each separate process works on its own frame. So, four processes might be running, working on frames 1, 2, 3, and 4.
After Effects is also (and unrelatedly) a multithreaded application, and many of the effect plug-ins are also multi-threaded. This means that each process---each instance of the After Effects application---can spread its work over mutliple processors and multiple threads. Even if Render Multiple Frames Simultaneously is switched off, you can see multiple processor cores chugging away on the same frame.
This distinction is important because of this tip, from After Effects Help:
"In many cases, performance is improved by using fewer than the maximum  number of processors for Render Multiple Frames Simultaneously multiprocessing,  even when you have enough RAM for all of the processors. After Effects is a multithreaded application that can also use other forms of multiprocessing beyond just Render Multiple Frames Simultaneously multiprocessing, and it is possible for the processors to become “overscheduled” if these threads are competing for the same resources as the background processes used for rendering with Render Multiple  Frames Simultaneously multiprocessing. Therefore, the best approach is to begin by using a small number of processors for Render Multiple Frames Simultaneously multiprocessing; and then increase the number of processors used until you find the optimum number for your computer system and compositions."
For more on this performance tip, see this post on my blog: "Performance tip: Don't overschedule your processors."