[Solved]-Complete code base is recompiled on every change in IntelliJ IDEA-scala

Turning on fsc might help (it sets the Scala compiler up as a daemon / service rather than starting it from scratch every time). In Scala facet of your project:

click "Use project FSC", then click Settings and select a compiler library for fsc.

If you're doing a larger project you probably want to use sbt to manage your build, as it does incremental compilation. IDEA has a good sbt plugin you can try.