rational_icthus,
I am glad it worked for you. I don't think it is constructing and returning a new sub each time. I think Perl is over-optimizing. The trick I used was to return a closure over $self which includes the desired subref.

You are correct, caching isn't always a solution. You might want to check out Memoize for future reference. In many cases, cache is the right solution but with limited resources you need to expire unused items from the cache and only keep the most used recent. The CPAN has all kinds of options. Just search for cache.

The argument checking is not perfect. There are much better modules such as Params::Validate. Everyone has their own way of doing things. Figuring out what works for you and those responsible for maintaining your code is what is important.

This problem is not restricted to ActiveState so that's not the proper course of action. If you are not familiar with perlbug then read up on it and send in a minimalistic test case.