regarding jar size, from http://get-scala.org/2.12 (mentioned in this thread already):

 	                2.9 	2.10 	2.11 	2.12
  Scala library 	9.0 	7.1 	5.7 	5.5
  Scala compiler 	11.5 	14.5 	15.5 	10.1
  ScalaTest (3.0.0) 	        10.5 	10.4 	7.0

data is in Megabyte. Compilation would be interesting, since I have read multiple times that it is slower due to a jvm bug. Only a few days ago for example: https://www.reddit.com/r/programming/comments/5ab948/scala_2...