Speaking of Scala Pro: "It should be noted that this version performs algorithmic improvements as well, and is therefore not directly comparable to the other Pro versions."
"... the benchmark also used a HashMap<Type, Integer> when it should have just stored a primitive int in Type; it also used a LinkedList where it should have used an ArrayDeque."
http://jeremymanson.blogspot.com/2011/06/scala-java-shootout...