Both with CF, Gradle 5+ much slower than Gradle 4

[entonio]

Hi. I'm trying to migrate a number of projects to more recent libs and JDK, as mentioned elsewhere.

I have a project (no modules, no subprojects) that spends 85s on compileJava with Gradle 4.x. It takes 325s with Gradle 5 and 6. If not using the CF, it takes 29s in either Gradle. These measurings were very consistent, down to the second. I've tried changing a number of other factors, but the relevant one is the combination of the CF with Gradle 5+. I should mention these are numbers for JDK 8. With JDK 11 (source level 8), the numbers are 115s, 135s, and 35s (so, not the same magnitude of slowerness).

Where could the problem be? How can I debug it?