in reply to
Re: Re^2: meaning of /o in regexes
in thread meaning of /o in regexes
I looked even further and the get magic (see sv.c Perl_sv_2pv and seek to the "Regexp" section) associated with stringifying a qr regex is actually pretty cheap. I'd guess any real performance loss is just from having to compile a regex more than once which unless you are doing some monster regex... isn't all that much of an issue.
printf "You are here %08x\n", unpack "L!", unpack "P4", pack