[exim] ${perl or ${run ?

How do you think, what is more expensive: one ${perl call
or three ${run calls (find -exec mv, find -delete, touch)?

It's greylisting without database. I'm rewriting it from Perl
http://wiki.exim.org/DbLessGreyListing to C (using ${dlfunc )
and intend to publish it there, but may be I should describe also
the ${run variant? Because compiling for ${dlfunc looks not too trivial,
and I enough well know only my OS (FreeBSD).