Salman Ahmed explains how shared buffers work in Postgres:
PostgreSQL is known for its robustness and performance right out of the box. However, different applications and different scales of data demand fine-tuning of various parameters to achieve optimum performance. One such significant parameter is shared_buffers, which, when configured correctly, can notably enhance the performance of your PostgreSQL database.
Read on to see what shared buffers are, why they are so important to Postgres, and how to figure out the right value to use.