Start up time of the JVM is 8s? I would definitely say that it depends on how their service initialization work. I have seen service accesses database to warm cache, calling other services to initialize their configuration, or simply reading config files before fully serving. And all that take time! There is no way against that regardless of your PL or runtime.
A typical no network initialized service in Java would start under 500ms (a p90, give or take).
A typical no network initialized service in Java would start under 500ms (a p90, give or take).