In 9.6, "make installcheck" in contrib/postgres_fdw takes a shade
under 3 seconds on my machine. In HEAD, it's taking 10 seconds.
I am not happy, especially not since there's no parallelization
of the contrib regression tests. That's a direct consumption of
my time and all other developers' time too. This evidently came
in with commit 7012b132d (Push down aggregates to remote servers),
and while that's a laudable feature, I cannot help thinking that
it does not deserve this much of an imposition on every make check
that's ever done for the rest of eternity.
regards, tom lane