Scala ships by default with sequential, lazy and parallel collections and actors.
Akka (akka.io) provides a different implementation of actors (which will replace the one in the standard library in the future), as well as Agents, STM, Transactors, ... for all your concurrency needs. Akka actors can actually outperform Erlang actors in core areas.
Spark (spark-project.org) provides a (Hadoop-like) framework for distributed collections.
Work is being done to make Scala collections run on GPUs, too.
I would argue that Scala's toolbox is pretty diverse and complete when dealing with parallel and/or concurrent problems.
Without facts I wouldn't claim that Scala is slower than Java/C++/C#.
Scala beats the shit out of Java in situations where Java has to work with boxed types instead of primitives like in ArrayList<Integer>, enables people to write fully generic algorithms supporting any number type without speed penalty.
Scala is certainly nicer than C++ because it just works and has far less weird corners or surprises. It lets you write code faster and gives you more time to actually optimize those places where it matters.
C# is pretty much a kitchen-sink language with many features bolted on in a non-othogonal way, unlike Scala. The unreliable VM doesn't help, although value types and the thing Mono did with SIMD is certainly nice.