anchor.diff:  * Term vectors. If `term_vector` information is provided by setting 
   `term_vector` to `with_positions_offsets` in the mapping, the `unified`
   highlighter automatically uses the `term_vector` to highlight the field.
  -Term vector highlighting is faster for highlighting multi-term queries like
  -`prefix` or `wildcard` because it can access the dictionary of terms for
  -each document, but it can be slower than using the postings list. The `fvh`
  -highlighter always uses term vectors.
  -
  -* Plain highlighting. This mode is used when there is no other alternative.
  +It's fast especially for large fields (> `1MB`) and for highlighting multi-term queries like
  +`prefix` or `wildcard` because it can access the dictionary of terms for each document.
  +The `fvh` highlighter always uses term vectors.
  +
  +* Plain highlighting. This mode is used by the `unified` when there is no other alternative.
   It creates a tiny in-memory index and re-runs the original query criteria through
   Lucene's query execution planner to get access to low-level match information on
   the current document. This is repeated for every field and every document that
  
positive.code: planner to get access to low-level match information for the current document.
  This is repeated for every field and every document that needs to be highlighted.
  If you want to highlight a lot of fields in a lot of documents with complex
  queries, we recommend using one of the other highlighters.
  
  [[fast-vector-highlighter]]
  ==== Fast vector highlighter
  
negative.code: This highlighter can be used on fields with `term_vector` set to
  `with_positions_offsets` in the mapping. The fast vector highlighter:
  
  * Can be customized with  a <<boundary-scanners,`boundary_scanner`>>.
  * Requires setting `term_vector` to `with_positions_offsets` which
    increases the size of the index
  * Can combine matches from multiple fields into one result.  See
  