You would benefit from more RAM for multiprocessing -- 2 GB per core at a minimum; 3 GB or 4 GB per core would be preferable.
You might try making your shock wave effect with the Displacement filter, using Radio Waves to generate the displacement map.
Walter Soyka, Principal
Keen Live, Inc.
Presentation, Motion Graphics & Widescreen Design
RenderBreak: A Blog on Innovation in Production