Those are the average iteration times over 20,000 iterations. If you want more accuracy add these 2 lines to prime.txt:
PercentPrecision=6
TimingOutput=4
From undoc.txt:
Quote:
You can adjust how many decimal digits of precision are displayed
in lines output to the screen. In prime.txt enter a value between 0 and 6:
PercentPrecision=n
You can alter the way the program outputs timings. In prime.txt set:
TimingOutput=n
Where n=1 for seconds with 3 digits of precision, n=2 for milliseconds
with 1 digit of precision, n=3 for milliseconds with 2 digits of precision,
n=4 for milliseconds with 3 digit of precision.

You can check other benchmarks here:
http://www.mersenne.org/report_benchmarks/
Your processor at 55M exponent is about 7075 ms in the chart (0.070.075 sec).