Allows the site administrator to specify a minimum length for autocomplete strings, to stop autocomplete from running SQL queries with potentially huge result sets.
It does this by replacing Drupals
Drupal.ACDB.prototype.search function with a little function that checks if the user-entered search string is shorter than the set minimum length. If so, execution is stopped. Once the search string is longer than the limit, the original function will be called to provide completion targets.