Which platform to use for fastest neo4j graph traversal?
In general, the fastest way to do traversals in neo4j is with the Java API. 
You might consider testing to see if it is fast enough before potentially prematurely optimizing. Try one of the python libraries w/ Cypher to see how it performs. 
If you do have to resort to the Java API, you can usually get away with writing a simple unmanaged extension (<50 lines of java/scala), and then call that from your python.
I have to do traversals on neo4j graph in real time. The graph contains around 200,000 nodes and 300,000 relationships. My main concern is that results should be super fast. 
Should I write the traversal algorithms in Java? Does Using python (py2neo or bulbflow) for the same has significant performance issues? My personal preference is for python here if performance is same for both python and java.