use strict;
use warnings;
use Benchmark 'cmpthese';

my @a = map log, 1..1e6;

cmpthese( -2, {
    1 => sub {[ map $_ * 4, @a ]},
    2 => sub {[ map $_ / (1/4), @a ]},
});

__END__

    Rate    1    2
1 7.70/s   -- -27%
2 10.6/s  38%   --