In my experience the Tomcat/JBoss tend to be a relatively large overhead, but since they can run multiple "war" files under the same overhead this is not as much a problem when running a single container for multiple applications. But when you containerize them you'd like to run one instance per application which will multiply the already significant overhead.
Not sure if this is what the GP was referring to, but just my 2 cents.
Not sure if this is what the GP was referring to, but just my 2 cents.