Maybe it is not actually the file-watching that adds the 90 minutes?
If you only used org.gradle.vfs.watch=false it could still be in the user-specific Gradle properties set to true, but when using the --no-watch-fs this should win and disable the file-watching.
Besides that it sounds pretty ridiculous that the file-watching adds 90 minutes.
If that is really the case, maybe you should report a bug.
But maybe you should try to enable --info or --debug to see what is actually happening and whether it might be something else that is happening, or maybe a build --scan could help if you can use it, but I’m not sure whether that would capture it if is happening after the BUILD SUCCESSFUL.
Maybe also the GitHub - gradle/gradle-profiler: A tool for gathering profiling and benchmarking information for Gradle builds could help to gather some insight.