#!/usr/bin/env perl
use strict;
use warnings;
use Benchmark();

Benchmark::cmpthese( -1, {
  sub_join_1  => sub { sub { join shift @_, @_; }->( ", ", 1 .. 100 );            },
  do_join_1 =>   sub { do  { local @_ = ( ", ", 1 .. 100 ); join shift @_, @_; }; },
} );

__END__

$ perl bench_do_sub_1.pl
              Rate  do_join_1 sub_join_1
do_join_1  17935/s         --       -73%
sub_join_1 66991/s       274%         --