Thanks for your suggestion.

This function is already implemented at perl level, and for historical reasons (read: legacy code) it handles Big™ data structures, resulting in 10/15 Mb strings.

And yes, this function has been selected as good candidate for XS/ Inline::C rewriting through basic profiling.

I thought it might be a valid experiment to learn XS. Probably I should discard Inline::C as a viable alternative because of internal distribution and servers update issues. Nevertheless I'm going to study Inline::C some more...