I don't know how to check for memory usage (rather than the blunt method of watching the task manager) but here are some speed tests. It appears from this test that they are very simlar in speed for this summing operation. For is the winner but i'm not sure its a noticable portion until you climb into the severl hundered thousand range. 
use strict;
use warnings;

use Benchmark qw(:all) ;

my $to = 10_000;

cmpthese(-5,
    {
        'Map100k' => sub { my $sum = 0;
                   map { $sum += $_ } 
                   1 .. 100_000;
                 },
        'For100k' => sub { my $sum = 0;
                   $sum += $_ for 1 .. 100_000;
                 },

        'Map10k' => sub { my $sum = 0;
                   map { $sum += $_ } 
                   1 .. 10_000;
                 },
        'For10k' => sub { my $sum = 0;
                   $sum += $_ for 1 .. 10_000;
                 },

        'Map1k' => sub { my $sum = 0;
                   map { $sum += $_ } 
                   1 .. 1_000;
                 },
        'For1k' => sub { my $sum = 0;
                   $sum += $_ for 1 .. 1_000;
                 },
    });

__END__
          Rate Map100k For100k  Map10k  For10k   Map1k   For1k
Map100k 18.6/s      --    -19%    -90%    -92%    -99%    -99%
For100k 23.1/s     24%      --    -88%    -90%    -99%    -99%
Map10k   187/s    905%    709%      --    -22%    -91%    -92%
For10k   239/s   1182%    933%     28%      --    -89%    -90%
Map1k   2077/s  11052%   8880%   1009%    770%      --    -13%
For1k   2387/s  12715%  10219%   1175%    899%     15%      --

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___________
Eric Hodges

In reply to Re: Re: Re: When would you choose foreach instead of map? by eric256
in thread When would you choose foreach instead of map? by jpfarmer

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