OLAP dedup over non elements

OLAP dedup() is highly inefficient when it's fed with non elements.

In a customer project a query similar tho the following returned a result in slightly more than 6 seconds:

persistedRDD.
  V().hasLabel("label1","label2").
  inE("edgeLabel1","edgeLabel2").outV().
  id().count()

The same query with dedup() added:

persistedRDD.
  V().hasLabel("label1","label2").
  inE("edgeLabel1","edgeLabel2").outV().
  id().dedup().count()

...took more than 120 seconds.