perl5.6.2 still blows away all newer releases performance and memory usage wise. 15 years ago the author was still active.
stableperl (http://blog.schmorp.de/2015-06-06-a-stable-perl.html) is a fork of perl 5.22 with a couple of tiny reversions that re-enable access to some internal state required by certain CPAN modules.
The author talks in other blog posts (http://blog.schmorp.de/2016-12-29-griefing-the-perl-api.html, http://blog.schmorp.de/2015-11-12-tidbits-why-coro-crashes-o..., http://blog.schmorp.de/2015-12-15-tidbits-cgipm-a-data-point...) about the decline of Perl's cohesion.
It's sad to see.
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EDIT: And now I'm being downvoted.
I have no problem with Perl, I watched the Perl 6 presentation when it was released with great interest.
Perl remains on my list of languages to learn (I know, I know...). It's up there. And that's why I said I was sad to see datapoints like the one I linked. I want Perl to keep going strong, and I hope it lasts another 20 years. I guess I added this comment because I wanted to find out if there was anything I could do.
I wouldn't mind learning more about this, perhaps via email (as an alternative to public discussion that might(?) start a flamewar).