cmpthese( -2,{
 list => sub { &list },
 shiftit => sub { &shiftit },
} );
__END__
5.8.3       Rate    list shiftit
list    126315/s      --    -62%
shiftit 333577/s    164%      --
5.6.2       Rate    list shiftit
list    135814/s      --    -61%
shiftit 343986/s    153%      --