With read-only work loads you can make shared_buffers very large, like 40% of RAM available to the database. Usually you would keep it lower because in a write heavy workload large shared_buffers causes checkpoints to have huge IO, but since you are not making changes in shared_buffers this will not happen.
You can also increase checkpoint_timeout to a very large value to prevent checkpoints, since you don't need them. WAL level can be minimal as well.
You can also run a CLUSTER command on one of your indexes to group data that is frequently accessed together into the same segment of disk so you can get more of it in a single IO operation.
You can also run the VACUUM FULL command during off-hours to get your tables vacuumed and statistics up-to-date. It's usually too much overhead to be worthwhile but since you are not doing updates you only have to do it once then don't need to worry about autovacuum being aggressive enough.
I don't think that removing locks will provide any benefit if your queries are truly read-only since ordinary read-only transactions do not require any locks
I would like to know if somebody is aware of tricks for optimizing PostgreSQL settings for a read-only database. I have a big read-only database (> 1.10^9 records splitted into ~ 10 tables) using GiST and Btree indexes, no foreign keys on tables at all.
I believe that not doing locks on pages could save some time as there's a lot of simultaneaous readers, but so far I've found nothing about this specific case in official documentation...
