Plugin version 4.5. introduces index table search engine. Index table is used to make the database queries faster and lighter. The index table must be generated before use.
Much faster lookup in the database
Less database-heavy operations - every keyword operation uses the table indexes, therefore no full table lookup, nor temporary tables are needed.
CAN index shortcode contents!
Good for big databases
Better relevancy calculation
Can't search for exact matches - the index table consists of separated keywords with relational and relevancy data. There is no way of determining the sorrounding keywords, therefore exact matching is not possible.
Can't search word inner parts, only beginnings and endings
for example "rat" NOT match "karate"
but "kar" will match "karate"
and "rate" will match "karate"
Has to be configured before use.
Only one index configuration for every search instance
Short answer, yes, you should. You definitely should if you:
Want to search shortcode content
Want to search tags, categories or any terms related to posts
Custom fields content
Have a big database of posts
You can index posts, pages and any custom post type. (products, forums, topics, etc..)