PERF: Code simplifications for performance testing

The behavior for computing derivatives is quite
different for local support and global support
transform types.  There were unecessary if-else
trees inside of looping constructs to switch
between the two algorithms.  This was unnecessarily
difficult to maintain and read.  By separting into
two distinct functions, the maintainence is easier
and future anticipated performance tuning will be
facilitated.

Change-Id: Idc9e38d4e864c8f3d9fdc5575bd1907cc2a118bc
Merge topic 'PrepareMattesForPerformanceTesting2'

1b464ccb PERF: Code simplifications for performance testing