In addition to performance improvements, we added an experimental option to run kapt, the Kotlin annotation processing tool, directly using Gradle workers. In some cases, this may significantly improve the overall build speed. To switch to the Gradle worker implementation, add the kapt.use.worker.api=true

Coworker tried this and it seemed slower… Looks like it uses

IsolationMode.PROCESS

which creates a new process for each worker… https://github.com/JetBrains/kotlin/blob/master/libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/internal/kapt/KaptWithoutKotlincTask.kt#L76 (edited)

IsolationMode.NONE

could be faster… https://docs.gradle.org/4.9/javadoc/org/gradle/workers/IsolationMode.html