GitHub (also) checks the vim-modeline to decide how the file should
be rendered.
These files are all in the POD format so add the vim-modeline so that
GitHub displays them in a formatted way.
(Note: adding `linguist-language=Pod` in .gitattributes does not work,
I created a GH support ticket for that a month ago but there have
been little progress on it.)
When running this test under heavy load
we cannot assume the delta between two system calls...
even when using a (nano)sleep
Most Continuous Integration system will fail on this
test at one point or the other.
