use strict;
use warnings;
use Benchmark qw/ cmpthese timeit /;

our @b = my @a = map log, 1..1e6;
 
timeit( 1, 'print "\$#a = $#a\n";' );
timeit( 1, 'print "\$#b = $#b\n";' );

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

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

__END__

$#a = -1
$#b = 999999
        Rate          b          a
b     7.70/s         --      -100%
a 10680591/s 138780824%         --
    Rate    1    2
1 7.76/s   -- -28%
2 10.7/s  39%   --