I've been having this same issue - the issue is quite reproducible for me,
and it has been for years.  I just finally grew tired of the issue and
decided to investigate it, and yes, the issue is org-agenda-show-new-time.

I also have invisible entries in the org buffer, and the call to
org-move-to-column apparently will move several lines forward, which causes
us to process the same lines over and over.

Wrapping the call to org-move-to-column with a let setting the
buffer-invisibility-spec to nil does fix the issue.


On Fri, Aug 23, 2013 at 8:08 AM Nick Dokos <ndokos@gmail.com> wrote:

> Carsten Dominik <carsten.dominik@gmail.com> writes:
>
> > I also do not expect negative consequences.  Please apply the patch,
> will you?
> >
>
> OK - patch attached. NB: there is at least one place where the "wrap the
> call to org-move-to-column" has been applied, in
> org.el:`org-comment-or-uncomment-region', presumably for exactly this
> reason. If this patch does not cause unexpected problem, then the
> wrapped setting above can be cleaned up.
>
>
> I hope it conforms to conventions but let me know of any problems.
> --
> Nick
>