Bottleneck when using auth/admin/realms/myrealm/users in my app

Maybe it is a silly observation, but did you try to increase you JVM heap in your docker configs? Like:

CMD java -XX:+PrintFlagsFinal -XX:+PrintGCDetails $JAVA_OPTIONS -jar java-container.jar

There is a fantastic blog that explain the memory issue with the JVM and docker here

CodeHunter