I've added three test classes:
1) org.hibernate.ogm.backendtck.batchfetching.MultiGetEmbeddedIdTest
2) org.hibernate.ogm.backendtck.batchfetching.MultiGetSingleColumnIdTest
3) org.hibernate.ogm.backendtck.batchfetching.MultiGetMultiColumnsIdTest

It seems that Neo4j it's very slow in the execution of 1 ( ~16 sec) and 3 (~10 sec). It takes only ~0.7 sec for 2
I suspect that in the Neo4j case it's related to the fact that when we have id with multiple columns we don't add unique constraints