Hello Aurelio,

Here's the configuration.

Server specs(Google Cloud Platform, 4cores,16GB)

=========================================

Odoo

to check cpu

cat /proc/cpuinfo | grep processor | wc -l

workers = (cores * 2) + 1

to check memory

cat /proc/meminfo | grep MemTotal | awk '{ print $2 }'

hard = 768MB

soft = 640MB

computation

limit_memory_hard = hard * 9workers * 1024 * 1024 

limit_memory_soft = soft * 9workers * 1024 * 1024

Odoo-server.conf

from 

#limit_memory_hard = 2684354560

#limit_memory_soft = 2147483648

to

limit_memory_hard = 7247757312

limit_memory_soft = 6039797760

Postgresql

sudo nano /etc/postgresql/9.5/main/postgresql.conf 

here's the link to compute \https://pgtune.leopard.in.ua/#/

Postgresql.conf

max_connections = 100

shared_buffers = 4GB

effective_cache_size = 12GB

maintenance_work_mem = 1GB

checkpoint_completion_target = 0.9

wal_buffers = 16MB

default_statistics_target = 100

random_page_cost = 1.1

effective_io_concurrency = 200

work_mem = 20971kB

min_wal_size = 1GB

max_wal_size = 2GB

max_worker_processes = 4