on my windows 10 box each package seems to eat ~1k of memory:

perl -we "sub mem{system qq(tasklist /FI \"PID eq $$\"|findstr perl)};
+ mem();bless {}, qq(A$_) for 1 .. 1000000;mem()"

perl.exe                     29356 Console                    1      6
+.616 K
perl.exe                     29356 Console                    1  1.353
+.656 K
[download]

and quite the same on my Linux box:

perl -we 'sub mem{system qq(cat /proc/$$/status | grep ^VmSize)}; mem(
+);bless {}, qq(A$_) for 1 .. 1000000;mem()'

VmSize:       23768 kB
VmSize:     1234168 kB
[download]

Obviously the package is empty..

perl -MDevel::Symdump -e "bless {},'notexisting';print Devel::Symdump-
+>new('noexisting')->as_string"

arrays

functions

hashes

ios

packages

scalars

unknowns
[download]

..holding just the AUTOLOAD

use strict;
use warnings;

my %before = %main::;
bless {},'nonexistent';
my %after = %main::;

foreach my $symbol (sort keys %after) {
    next if exists $before{$symbol}; 

    local *myglob = $after{$symbol};
    if ( defined *myglob{HASH} ) {
        my %val = %{ *myglob{HASH} };
        print "HASH \%$symbol = ( ";
        while(  my ($key, $val) = each %val )  {
            print "$key=>'$val', ";
        }
        print ")\n" ;
    }
}

__END__

HASH %nonexistent:: = ( AUTOLOAD=>'*nonexistent::AUTOLOAD', )
[download]

..but: For various obscure reasons, typeglobs are always created with a Null SV in the SCALAR slot.

L*