package Book::HeavySub;

use strict;
use Benchmark;

sub bar { 
    my $class = shift;

    my ($x, $y) = (100, 100);
    $y = log ($x ** 10)  for (0..20);
};

timethese(100_000, {
    method   => sub { Book::HeavySub->bar()                 },
    function => sub { Book::HeavySub::bar('Book::HeavySub');},
});