This probably isn't much faster, but as a personal preference I avoid using map in void context: 
sub propogate {
  my($array, $from, $to) = @_;

  foreach (@$array) {
    foreach (@$_) {
      $_ = $to if $_ == $from;
    }
  }
}

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In reply to Re: Fast search/replace? by chipmunk
in thread Fast search/replace? by weingart

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