Are you using Oracle Database 12c? If so, please take a look at the latest support for Apache Jena 2.11.1 (that was released a couple of days ago). The latest support can push down the property path into the DB for a more efficient execution.
Please take a look at the following post:
Hope it helps,
In addition, when pushing property path execution down into the DB, please note that the DB uses a depth-limited search for * and + with a default depth of 10. The depth limit can be adjusted using an ALL_MAX_PP_DEPTH(n) hint (with ORACLE_SEM_HT_NS through Jena Adapter). Using a depth limit of 0 switches from a depth-limited algorithm to a true unbounded path search, which is probably what you want for subClassOf*. The depth limited search is best for properties with a large fanout at the instance level.
For example, to get an unbounded property path search, use PREFIX ORACLE_SEM_HT_NS: <http://oracle.com/semtech#all_max_pp_depth(0)> in your query to the SPARQL endpoint.