Adjust a few performance numbers

These did not yet trigger a failure, but are more than 1% away from the
expected value. Since I now start collecting logs to investigate
deviations from the expected value, it makes sense to reset them. This
way we know that every significat deviation was caused since this
commit.

I only updated bytes_allocated numbers, as these are (mostly)
deterministic. Other depend, AFAIK, on sampling timing, so I did not
bother.
Correctly round when calculating the deviation