The setuid bit doesn't matter on my system, same result with or without. AFAIK the only difference is that setuid forces the taint flag to be set, otherwise you must set it explicitly.

What system are you running perl on?

Tried with a C wrapper around your script as described in perlsec?

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}