amcheck eating most of the runtime with wal_consistency_checking

Hi Peter,

While testing wal_consistency_checking, I have noticed that by far
most of the runtime is spent within the regression test check_btree on
the series of three queries inserting each 100k tuples.  This also
eats most of the run time of the test on HEAD.  Could we for example
consider inserting less tuples with a lower fillfactor to reduce the
runtime of the test without impacting its coverage in a meaningful
way?

Thanks,
--
Michael