IntelliJ very slow with scala play framework, 2018.06

The editor is already painfully slow with scala play framework and the hundreds of implicits we have in our project. When building call hierarchy consumes all CPU for about 2-3 minutes. Often when typing code the editor starts consuming all CPU, practically hangs for 1-2 minutes. This happens 50-100 times per day. Debugger is even worse, takes about 10-20 minutes to start debugging and stepping each line can cost minutes.
We have a team of 4 developers, we all experience the same problem for the last 1-2 years, and some of them abandoned using IntelliJ for this reason.

My hardware: T580 with i7 8th generation, 16GB RAM  with 12GB set for IntelliJ. Actual memory consumption is between 6-8 GB. Ubunbtu 17.10.
Colleagues use other versions of Lenovo T series with Ubuntu an one uses Windows, but the problems with IntelliJ are similar.

Project uses play framework, local MySQL DB (with very little data for easy testing) and slick for DB. Our guess is that problems are caused by implicits, where play framework brings in lots of them.

IntelliJ IDEA 2018.1.5 (Ultimate Edition)
Build #IU-181.5281.24, built on June 12, 2018
JRE: 1.8.0_152-release-1136-b39 amd64
JVM: OpenJDK 64-Bit Server VM by JetBrains s.r.o
Linux 4.13.0-38-generic