I am very happy that this post was created and that it was selected as a Staff Pick. This notebook gives great results, but if we repeat the optimization 20 times, the computation time will be around 20 days. The computation might be made much faster using advanced Mathematica's functions. However, version 7 can solve simultaneous equations much faster than later versions. I am currently trying to optimize the arrangement of point-like scatterers for a transcranial ultrasound lens that can uniformly stimulate the brain with ultrasound for the treatment of Alzheimer's disease.

Thank you for calling me the Japanese way.
Thank you for your interest and suggestion.
I am now using some workstations with AMD EPYC 7763 (64Core, 2.45GHz), with Intel Xeon 6154 (3.0GHz 18 Core ) and so on.
Your suggestion is fruitful.
Such a suggestion might be the greatest benefit of this community.
Certainly, although the optimizing process is iterative, the loops or sums within the iteration should be made faster by parallelization.