In addition to chorus of replies that you now will get on perl/Tk, I'll make my suggestion to move to Tcl::Tk.

It has the BLT package, the very graph expert for Tk, see http://vkonovalov.ru/cgi-bin/perl-tcltk-wiki.cgi/38.

This requires Tcl/Tk (via Tcl::Tk CPAN module), which is similar to perl/Tk but more advanced