Report timings with microsecond resolution

In case one has a small problem to solve, where
completion is reached within a few milliseconds,
then four decimal places are not enough to accurately
represent the timings of all the separate sub-steps.
Thus, we extend the reported timings to include
six decimal places.

Change-Id: Iaf88a94a1b8896ea7370c75b1de2f05d8671206e