There is no science, your speeds will always improve if you increase value "x", or decrease "value "y".
The problem is the suggested tweaks, improve performance for most users.
But I've seen reports, where wal_buffers = 32MB would decrease performance, or when changing a value to one of the recommended values PostgreSQL would still stop running.
I wouldn't spend too much time, trying to tweak the settings even further.
Read: https://de.pokertracker.com/forums/v...p?f=15&t=30450 where other users have already attempted to that without improving results.