in reply to lighter alternative to CGI.pm
Damn. You're probably really close to being able to invert the structure, and turn the HTML into a template. But that won't help your performance issue unless you can run mod_perl.
Is this something you could use PerlScript for? You'd be getting some Cookie- and form-handling for free, and might be able to avoid CGI.pm (or a lighter alternative) entirely.
The Perl-Win32-ASP FAQ has details.