Reducing the join and concatenation to a simple example without any file i/o, I don't get the same result when Benchmarking.

use strict;
use warnings;

use Benchmark qw{ cmpthese };

my @arr = ( q{abc} ) x 10000;

cmpthese( -5, {
   concat => sub { my $ret; $ret .= $_ for @arr; return $ret; },
   join   => sub { my $ret = join q{}, @arr; return $ret; },
   } );

[download]
$ ./spw1003500
         Rate concat   join
concat  994/s     --   -70%
join   3310/s   233%     --
$

[download]

Perhaps something else is skewing your timing.

Cheers,

JohnGG

In reply to Re: Concatenate or Join? by johngg
in thread Concatenate or Join? by perldaemon

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