"Glen Low probably knows as much about high-performance computing (HPC) on Mac OS X as anyone outside Apple. He is author of macstl, a C++ library that takes advantage of the vector engines in PowerPC and Intel chips to make almost obscene performance gains over scalar code." There is an interview on MacResearch in which he gives an insight into the tools of the trade. If you are looking to take maximum advantage of the performance gains possible then this should be essential reading.