use strict; use warnings; use Benchmark qw{ cmpthese }; our %a; $a{ $_ } = "foo" for 1..1000; $a{ 1 + int rand 1000 } = '' for 1..10; cmpthese( -3, { Joost => 'scalar grep { $_ ne "" } values %a', fishbot => 'scalar grep { $a{$_} ne "" } keys %a', other => 'scalar grep { ! /^$/ } values %a', OP => 'scalar grep { $a{$_} !~ /^$/ } keys %a', } );