One of the few languages that, when dying, appears to increase in use.
One of the greatest problem is compilation time, however since computers get better this will be reduced. And still the team is working to bring more Scala <-> Java interop and a newer compiler which will bring compilation times down, too.
Saying that, Scala 2.12 will still be relatively slow compared to say, C, Go, Java and similar languages not high up on the abstraction ladder. The real compiler speed up will be coming with Dotty (Scala 3). Martin Odersky estimates that Dotty will be up to 4X faster than present day Scala.
Improved incremental compilation of #scala in the
making yields 10-40x compilation speedups:
https://github.com/sbt/sbt/issues/1104#issuecomment-188529825
and After turning on the java8 backend in Scala, our
bytecode size decreased by 50% and compile times
decreased by 75%. Amazeballs!
by some Scala devs.