Sounds normal to me. Note that setting query.batch=true might help a bit. Also note that the graph structure, in particular the number of repeat steps, is important. Finally, note that caching in the storage backend (in addition to caching inside JanusGraph) plays a role, see:
http://yaaics.blogspot.com/2018/04/understanding-reponse-times-for-single.html

Best wishes,    Marc