Comment 2 for bug 1065146

It is also possible that the simulation used was so small that it could not take advantage of multiprocessing. You might try to increase the number of chunks when defining the volume -- see http://claudia.intec.ugent.be/software/python-meep/python_meep_documentation.html#defining-the-waveguide-structure

My architecture is similar, Ub. 12.04, intel core i3 and I observe slight improvement when using 2 processes with MPI. However, three or more processes are slower, because the bottleneck is probably in the speed of RAM.