I have similar problem when I run Jnit test. I have just created a new Kotlin project and my project has just 12 classes at the moment.
I am using Java 1.8.0_45 + Android Studio 3.0 + Kotlin1.1.51 + BuildTool 26.0.1 in MacOS Siera 10.12.5.
As you see in the attached screenshot, the compile time is incredibly slow. I don’t have any idea what’s going on.