Is performance different with running a single instance or several with replication set up?

Question

If I run a single query, for example, execute an algorithm, does it make a difference (performance-wise) whether I run it on a single instance, or if I have several instances with replication set up?

Answer 1

For read queries, there is no difference in performance because the communication overhead between the main instance and replicas is not measurable in most cases. For write queries that are modifying a lot of objects, the communication might have a measurable overhead if you use the SYNC mode. However, you can avoid this by using ASYNC mode, in which the main instance can commit a transaction without waiting for the replica to confirm that it received the transaction.

Here is a post with detailed information about Memgraph's replication feature.