$ find 5.18.0 -name \*.pm | xargs grep -wl 'use Config' | wc -l
57
$ find site_perl/5.18.0 -name \*.pm | xargs grep -wl 'use Config' | wc -l
107
$ corelist Config Config::Perl::V

Data for 2013-08-20
Config was first released with perl 5.00307

Data for 2013-08-20
Config::Perl::V was first released with perl v5.17.9
$ time perl -V:ptrsize
ptrsize='4';
0.005u 0.003s 0:00.00 0.0%      0+0k 0+0io 0pf+0w
$ time perl -MConfig -wE'say $Config{ptrsize}'
4
0.001u 0.005s 0:00.00 0.0%      0+0k 0+0io 0pf+0w
$ time perl -MConfig::Perl::V -wE'say Config::Perl::V::myconfig ()->{config}{ptrsize}'
4
0.007u 0.002s 0:00.00 0.0%      0+0k 0+0io 0pf+0w