verify_at_commit can take a long time, especially during rebuild_db after reconstruct and similar operations. It should give a progress indicator if more than e.g. 100 revids are in the bag.

<hr /><i>drh added on 2010-10-03 23:53:44:</i><br />
Check-in [5f0201030cbf365207] cancels the verify_at_commit() on 
the "fossil reconstruct" command since that call is not really needed
in that context.

The verify_at_commit() routine is one of the
[/doc/trunk/www/selfcheck.wiki | safety checks]
that Fossil runs on every repository change in order to make sure
that nothing happens that would corrupt the repository.  Such checks
are a nice safety feature for day-to-day check-ins.  But the extra
layer of checking does not seem necessary for when a repository is
being constructed from scratch.