[David Nolan]

I have exactly the same problem, and I can’t believe that the composition doesn’t need to use more that 10% of the RAM
I have just switched from CS3 to CS4, and I am finding that compositions which took 1-2 hours to render on CS3 are taking 15 hours on CS4.

I have a quad-core 2.4Ghz processor and 8Gb RAM on Windows XP 64.
When I try to render using the multiprocessing option the render uses just 10% of the RAM and takes hours.
When I turn multiprocessing off, After Effects is able to use 60% of the RAM, but it still takes as long.

It cannot be that the switch to CS4 has significantly REDUCED my working efficiency and output.
Any help to fix this problem would be greatly appreciated.
Thanks