title: OrientDB slow traversal after depth 4
body: <p>OrientDB is slow after the traversal is greater than depth 3. (depth 3 took 4 seconds, depth 4 took 11, depth 5 took 37 seconds)</p>
  
  <p>My query is: TRAVERSE * FROM (select from products where pid = '73') while $depth&lt;=5</p>
  
  <p>Products extends from V and I have an index type UNIQUE (field pid) with engine SBTree.
  When I try with depth 1 until 3 works fine.
  I compared with Neo4j and took 3 seconds in depth 5 with the same data.
  I am working with OrientDB 2.1.5
  Please help me to improve this.
  Thanks.</p>