AI is a vast field, you can't just generalize that "AI stuff cannot be implemented in Perl". Many of the AI-related branches are
closely related to heavy calculus, which if, of course, stupid to implement entirely in Perl.
However, there are quite a lot of other AI-related features that can be perfectly written in Perl with no loss in performance and a
dramatical gain in maintainance. Anything about data processing just can't be maintained easier. If your data is based on a formal
syntax definition, you may want to write the parser in a low-level language and you *will* win performance, but if you deal with
arbitrary data, you may want to have a Perl wrapper around your parser to have some real fun cleaning it up.
In my company, we do a lot of automatic data processing based on arbitrary source documents which are scrutinized in all ways to try
to make some sense out of them. There are quite a lot of algorithms that we have successfully implemented entirely in Perl: for
example, those that detect lexical congestions in a raw text in order to filter out junk before parse attemps are applied to
sections which are considered as most probably pertinent.
If you want to check out what performance Perl can attain, check out www.jazzvalley.com. Every time you click, there are thousands
of objects being instanciated (100% object-oriented design of the whole site, and it is pure Perl).