It looks like you're still using Neo4j 2.3. Have you tried using newer versions of Neo4j? There have been some pretty substantial performance improvements.
Additionally, Neo4j does support clustering with their Enterprise edition. It also has much better tooling (better metrics/logging, backups, etc.). It is AGPL licensed, so there's no reason not to use it really.
Additionally, Neo4j does support clustering with their Enterprise edition. It also has much better tooling (better metrics/logging, backups, etc.). It is AGPL licensed, so there's no reason not to use it really.