IntelliJ IDEA build extremely slow with JDK 11 on MacOS

Question

For several weeks, our development team has been suffering from very slow build times in IntelliJ IDEA 2018.3 on MacOS since switching from JDK 8 to JDK 11. Build times for a full build went up from ~5 min. to ~20 min.

Answer 1

Found this workaround in the comments of bug ticket https://youtrack.jetbrains.com/issue/IDEA-201978 which is working for us, I'm posting it here as you won't find it via Google for whatsoever reason.

As a temporary workaround please add the following to IDEA VM options: -Dcompiler.ref.index=false and restart IDEA.