The post mentions using tombstones for deletion, but I was under the impression that the variance benefits of Robin Hood hashing weren't realized unless you performed a backwards shift on the remaining elements instead of using a tombstone.

See these posts for more information:

http://codecapsule.com/2013/11/11/robin-hood-hashing/

http://codecapsule.com/2013/11/17/robin-hood-hashing-backwar...

Unfortunately there's not great information around the overall CPU performance impact of using a shift vs. tombstone.