Add a load balancer just as Michel said and performance & latency improves substantially. I got some mind-boggling results no other graph DB came even remotely close to it.
DGraph works internally very differently from many other databases. Setting up a DB cluster in Oracle or Postgres for that matter takes some non-trivial configuration and you come to expect that.
In Dgraph, however, you just dispatch all incoming requests using a load-balancer and your all set. It really is that trivial.
The beauty of that setup becomes a true beast when you place a transparent http-cache such as varnish in front of the load-balancer. That setup gives you constant sub-millisecond response time no matter what you throw at it. Completely bonkers, you have to measure that.
The load balancing capability really needs strong emphasis in the cluster section of the docs because that functionality alone saves you substantial time, effort, and even some headeche.