$t=time; $a[ $_ ] = $_ for 1 .. 1e6; print time() - $t; print total_size \@a;;
0.208095073699951
32388768

$t=time; $h{ $_ } = $_ for 1 .. 1e6; print time() - $t; print total_size \%h;;
0.586999893188477
112277576