You can use the Neo4j graph database to store Associativy graphs. If you're using Neo4j as the underlying storage for Associativy graphs, you can count on better performance and scalability if a graph is enormously huge.
To be able to use Neo4j you need to install the Neo4j driver module. When this is done, you can write graph providers that use INeo4jConnectionManager as a connection manager, thus utilizing a Neo4j database. For an example, look at the Notions demo instance: Associativy.Instances.Notions.Neo4jNotionsGraphProvider is a Neo4j graph provider.