I have taked a look in the module B::Size, as our friend stvn pointed it, and based in a code of Apache::Status I made this function that prints a package size report:

  package_size('main');
    
  sub package_size {
    my($package) = shift ;
    
    require B::TerseSize ;
  
    print("Memory Usage for package $package\n\n");
  
    my($subs, $opcount, $opsize) = B::TerseSize::package_size($package
+);
  
    print("Totals: $opsize bytes | $opcount OPs\n\n");
  
    my($clen, $slen, $nlen);
  
    my @keys = map { $nlen = length > $nlen ? length : $nlen; $_; }
                   ( sort { $subs->{$b}->{size} <=> $subs->{$a}->{size
+} } keys %$subs );
  
    $clen = length $subs->{$keys[0]}->{count};
    $slen = length $subs->{$keys[0]}->{size};
  
    for my $name (@keys) {
      my $stats = $subs->{$name};
      if ($name =~ /^my /) {
        printf "%-${nlen}s %${slen}d bytes\n", $name, $stats->{size} ;
      }
      else {
        printf "%-${nlen}s %${slen}d bytes | %${clen}d OPs\n", $name, 
+$stats->{size}, $stats->{count} ;
      }
    }
  }
[download]

And here's an output example:

Memory Usage for package main

Totals: 24699 bytes | 212 OPs

package_size 9526 bytes | 212 OPs
*ENV{HASH}   3372 bytes |   0 OPs
*SIG{HASH}   2943 bytes |   0 OPs
*INC{HASH}   1378 bytes |   0 OPs
*_{HASH}      228 bytes |   0 OPs
*INC{ARRAY}   175 bytes |   0 OPs
*_{ARRAY}     125 bytes |   0 OPs
*0{SCALAR}     69 bytes |   0 OPs
*1{SCALAR}     69 bytes |   0 OPs
*ARGV{ARRAY}   60 bytes |   0 OPs
*_{SCALAR}     26 bytes |   0 OPs
[download]

Enjoy!