Mac OS X       Serial:  18.185s
Mac OS X     Parallel:   6.687s  threads
Mac OS X     Parallel:  42.526s  non-threads

CentOS 7 VM    Serial:  10.832s
CentOS 7 VM  Parallel:  23.849s  threads
CentOS 7 VM  Parallel:   2.993s  non-threads