Freelinking module, but reverse the dependency?

I have articles with words that are acronyms and other technical jargon that I want to convert into links to their definitions. I know the freelinking module allows me to do this by formatting the wikiwords: it only links words [[like this]] or LikeThis.

I want to do something different: I don't want the writer of the term to have to markup the word as a WikiWord, I I want freelinking to parse every word and compare it to a set of terms that map to pages containing definitions.

For example a page contains several terms, each term maps to one definition page. But a definition page can define many terms.

So the freelinking process would have to:

$words = array();
preg_match_all("/\w+\b/", $node->content, $words);
$terms = array();
$replace = array();
foreach ($words as $word) {
  if ($term = _find_term_matching($word)) {
    $words[] = $word;
    $replace[] = '<a href="'. $term->href .'" title="'. $term->title .'">$word</a>';
  }
}
str_replace($words, $replace, $node->content);

My concern is that this requires a filter which performs a full text search of a (probably large) list of words against a list of terms indexing node pages containing definitions, such a filter will not perform well. What do you think if the $words only contained distinct values?

I'm wondering if anybody has tried triggering on the reverse dependency, so that the filtering process is called when I save the definition; it then searches for nodes that contain the term, and updates them. Does that perform better, assuming these pages have been indexed by search?