How do I limit the memory use of Airsonic?

I have installed the LSIO docker/airsonic container on my synology nas and I was wondering how to lower the huge memory use of airsonic. I have already tried the following but it seems to do nothing.
The memory use is still very high on idle around the 1,3GB for doing nothing. Any idea how to solve this? This will explain what those commands are doing but the only other option you’ve really got to limit memory usage is using the memory limit features of docker-compose:

Okay thanks I will take a look at and give it a Try!

Just a few questions more, what is the minimum memory I can set for the container to still work properly?

And if I set a memory limitation for the docker is this still needed?
- JAVA_OPTS=-Xmx256m -Xms256m