Advanced
Tuning Postgres for better performance if "cold" reads are slow
If the first time you access certain pages is slower than the second time, and you have enough memory available, consider updating your shared\ buffer
If the first time you access certain pages is slower than the second time, and you have enough memory available, consider updating your shared_buffers.
shared_buffers = 256MB (or larger if you have enough room)
see
https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server