If you're using v10, the first thing I suggest is using Odoo with an upgraded PostgreSQL version, there has been a LOT of performance changes since 9.3, and now its even better in 9.6 with Parallel execution of sequential scans, joins and aggregates. That's first.

Then comes your configuration, which with 16GB should be near of this:

max_connections = 100

shared_buffers = 4GB

effective_cache_size = 12GB

work_mem = 41943kB

maintenance_work_mem = 1GB

checkpoint_segments = 64

checkpoint_completion_target = 0.9

wal_buffers = 16MB

default_statistics_target = 100

Thank you very much. :)

(y)