bug#57079: 29.0.50; Performance of seq-uniq is not very good

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: stefan@marxist.se,  57079@debbugs.gnu.org
> Date: Tue, 09 Aug 2022 20:03:46 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > My point is that it will never be as fast as the implementations
> > Stefan deleted, replacing them with seq-uniq.  My point is that those
> > changes just made several places in Emacs slower, even after your
> > speedup, for no good reason.  Those deleted functions, if they needed
> > to be deleted, should have been replaced by a different
> > implementation, which doesn't support TESTFN and is therefore faster,
> > as the original implementations, now deleted, were.
> 
> The performance of the new seq-uniq (called with no TESTFN) is identical
> to the old gnus-delete-duplicates -- it's the same code.

Yes, and delete-dups on a copy is faster.