#!/usr/bin/env perl

use strict;
use warnings;
use autodie qw{:all};

use Time::HiRes qw{time};

my $source_file = "$ENV{HOME}/local/dev/test_data/text_G_1";
my $concat_file = 'pm_1171789_concat_files.out';
my $files_to_concat = 10;

print "Source file:\n";
system "ls -l $source_file";

{
    print "*** SLURP MODE ***\n";

    my $t0 = time;
    my ($t1, $t2);

    open my $out_fh, '>', $concat_file;

    for my $file_number (1 .. $files_to_concat) {
        local $/;
        $t1 = time;
        open my $in_fh, '<', $source_file;
        print {$out_fh} <$in_fh>;
        $t2 = time;
        print "Duration (file $file_number): ", $t2 - $t1, " seconds\n";
    }

    print 'Total Duration: ', $t2 - $t0, " seconds\n";
    print 'Average Duration: ', ($t2 - $t0) / $files_to_concat, " seconds\n";

    print "Concat file:\n";
    system "ls -l $concat_file";

    unlink $concat_file;
}

{
    print "*** RECORD MODE ***\n";

    my $t0 = time;
    my ($t1, $t2);

    open my $out_fh, '>', $concat_file;

    for my $file_number (1 .. $files_to_concat) {
        $t1 = time;
        open my $in_fh, '<', $source_file;
        print {$out_fh} $_ while <$in_fh>;
        $t2 = time;
        print "Duration (file $file_number): ", $t2 - $t1, " seconds\n";
    }

    print 'Total Duration: ', $t2 - $t0, " seconds\n";
    print 'Average Duration: ', ($t2 - $t0) / $files_to_concat, " seconds\n";

    print "Concat file:\n";
    system "ls -l $concat_file";

    unlink $concat_file;
}

##</code><code>##

$ pm_1171789_concat_files.pl
Source file:
-rw-r--r--  1 ken  staff  1000000000  8 Feb  2013 /Users/ken/local/dev/test_data/text_G_1
*** SLURP MODE ***
Duration (file 1): 10.8527989387512 seconds
Duration (file 2): 10.3008499145508 seconds
Duration (file 3): 9.28949189186096 seconds
Duration (file 4): 9.32191705703735 seconds
Duration (file 5): 9.52065896987915 seconds
Duration (file 6): 8.99451112747192 seconds
Duration (file 7): 8.9400429725647 seconds
Duration (file 8): 11.1913599967957 seconds
Duration (file 9): 8.92997598648071 seconds
Duration (file 10): 9.06094002723694 seconds
Total Duration: 96.4215109348297 seconds
Average Duration: 9.64215109348297 seconds
Concat file:
-rw-r--r--  1 ken  staff  10000000000 15 Sep 09:25 pm_1171789_concat_files.out
*** RECORD MODE ***
Duration (file 1): 8.15429711341858 seconds
Duration (file 2): 8.53961801528931 seconds
Duration (file 3): 8.15934777259827 seconds
Duration (file 4): 9.53512001037598 seconds
Duration (file 5): 11.1551628112793 seconds
Duration (file 6): 12.2594971656799 seconds
Duration (file 7): 10.3394339084625 seconds
Duration (file 8): 10.799164056778 seconds
Duration (file 9): 11.6248168945312 seconds
Duration (file 10): 12.0355160236359 seconds
Total Duration: 102.602620124817 seconds
Average Duration: 10.2602620124817 seconds
Concat file:
-rw-r--r--  1 ken  staff  10000000000 15 Sep 09:27 pm_1171789_concat_files.out