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

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Tue, 9 Aug 2022 09:11:07 -0700
> 
> Severity: minor
> 
> `seq-uniq' is not very performant compared to `-uniq' (from dash.el) and
> even slower compared to the recently removed `gnus-delete-duplicates':
> 
>     (benchmark-run 10000 (seq-uniq '(a c b c c a d)))
>     => (0.355001481 1 0.2518970439999748)
> 
>     (benchmark-run 10000 (-uniq '(a c b c c a d)))
>     => (0.006599549 0 0.0)
> 
>     (benchmark-run 10000 (gnus-delete-duplicates '(a c b c c a d)))
>     => (0.0034537929999999997 0 0.0)
> 
> Could we improve the performance of `seq-uniq' for lists?

What's wrong with using delete-dups for your cases above?