That's exactly it. Plus add in all of the Spring Boot stuff (autodiscovery/autowiring, behaviour that gets added simply because a .jar is on the classpath, etc

That's exactly it. Plus add in all of the Spring Boot stuff (autodiscovery/autowiring, behaviour that gets added simply because a .jar is on the classpath, etc etc) and you end up with a pretty large footprint for a pretty tiny app. For reference too, the deployment artifacts with Go are ~5MB vs. a 70MB .war file. We've also just used really simple packages (the built-in net/http server for Go vs. embedded Tomcat, gorilla/mux vs. the Spring class annotations for routing), and I suspect that dramatically cuts down on the footprint too.