use Benchmark qw( cmpthese );

@array = ( 'aaa' .. 'zzz' );

cmpthese ( -3, {
  mapped => q{my %hash = map{$_=>0} @array},
  opped  => q{my %hash; @hash{@array} = (0) x @array},
} );

__END__
         Rate mapped  opped
mapped 65.9/s     --   -45%
opped   120/s    82%     --