为什么提高plackup（或starman）的内存使用率？

use strict;
use warnings;

my $app = sub {
    my $mem = `ps -o rss= -p $$`;
    $mem =~ s/^\\s*|\\s*$//gs;
    return [ 200, [ \'Content-Type\' => \'text/text\' ], [ $mem ]];
};

plackup

plackup -r

starman

use strict;
use warnings;
use LWP::UserAgent;
my $ua = LWP::UserAgent->new;
my $req = HTTP::Request->new(GET => \'http://localhost:5000\');

my $old_mem = 0;
print \"req#\\tmem\\n\";
foreach my $i (1..1000) {
    my $res = $ua->request($req);
    (my $mem = $res->content) =~ s/\\D//g;
    next if( $mem == $old_mem );
    print \"$i\\t$mem\\n\";
    $old_mem = $mem;
}

plackup                 plackup -r              starman
req#    mem             req#    mem             req#    mem
1       7780            1       3924            1       3280
2       7800            2       4296            5       3728
3       7804            3       4304            8       3280
                        ...                     ...
                        ... deleted             ... deleted
                        ...                     ...
                        839     4596            994     3912
                        866     4600            998     3908
                        962     4604            1000    3912

plackup -r

starman

# cpanm Plack Starman
Plack is up to date. (0.9979)
Starman is up to date. (0.2010)
# perl -v

This is perl 5, version 12, subversion 3 (v5.12.3) built for darwin-thread-multi-2level