Rate dispatch    elsif
dispatch  9363/s       --     -12%
elsif    10627/s      13%       --

##</code><code>##

my %dispatch=(
    A=>sub { split(/!/,$_[0]); },
    ...
);

sub dispatch {
   my $x=$letters[random($nLetters)];
   my $y='xyzzy!' x random(1000);
   if (exists $dispatch{$x}) {
      $dispatch{$x}->($y);
   } else {
      warn "Huh?";
   }
}