C:\test>p1
cmpthese -3, {
    pack_32bit => q[ my $packed = pack 'V*', 1 .. 1e6 ],
    vec_32bit  => q[ my $packed = ''; vec( $packed, $_, 32 ) = $_ for 1 .. 1e6 ]
};;
           s/iter  vec_32bit pack_32bit
vec_32bit    5.58         --       -12%
pack_32bit   4.94        13%         --