%hash = ();
    foreach $_ (@array) {
	  $hash{getkey($_)} = $_;
    }

##</code><code>##

  my %res = map {
	$_ => do {
		my $re;
		$re .= $translations{$_} for split //;
		$re;
	} if !$res{$_};
  } @words;

##</code><code>##

  my %res;
  foreach my $word (@rw) {
	$res{$word} ||= do {
	  my $re;
	  $re .= $translations{$_} for split //,$word;
	  $re;
	}
  }

##</code><code>##

Benchmark: running foreach, map_it for at least 5 CPU seconds...
   foreach:  6 wallclock secs ( 5.34 usr +  0.00 sys =  5.34 CPU) @ 286.87/s (n=1531)
    map_it:  5 wallclock secs ( 5.15 usr +  0.01 sys =  5.16 CPU) @ 134.77/s (n=695)

##</code><code>##

  my @b = (7,5,5,6);
  my @a;
  @a = map { $_ > 5 ? $_ : $a[0] } @b;