use Benchmark qw(:all);
use File::Slurp;

my $file1 = 'file1.txt';
my $file2 = 'file2.txt';

my $count = 1000;

cmpthese($count, {
        'File1' => \&file1,
        'File2' => \&file2,
    });

sub file1{
    my @array = ( 1..100 );
    foreach ( @array ){
        open ( FILE1, ">>$file1" );
        print FILE1 "$_\n";
        close FILE1;
    }
}

sub file2{
    my @array = ( 1..100 );
    foreach ( @array ){
        append_file( $file2, "$_\n" );
    }
}

##</code><code>##

        Rate File2 File1
File2 3.24/s    --   -8%
File1 3.51/s    8%    --