This add-on is aimed at large forum with tens of thousands to hundreds of thousands or more threads in a single forum. Smaller forum do not gain much benefit from this add-on.
Member List/Forum/conversation lists:
MySQL/MariaDB implements 'early row lookup', when combined with LIMIT & OFFSET with a large offset, results in the large select statement pulling in more data than is required. Maybe one day MySQL/MariaDB will fix this. Maybe.
This causes an issue as this how conversations and threads implement paging.
This addon provides some optimized query for getting threads in a forum with large number of threads, or for conversations with a very high page count.
Ideally conversations would implement the position system like posts do, which would be even faster than using sub-selects to force 'late row lookup'.