High memory usage (Jenkins in Docker)

Hey there,
I’m running the jenkins/jenkins:lts-jdk11 docker image on my VPS which I installed through Portainer.
When I check htop on my Server, memory usage is at 4GB (out of 16) which is almost entirely caused by Jenkins. I run ~4 builds a day and this is in idle right now.
There’s also a bunch of processes. Why is this the case and how could I reduce memory usage?

Here’s a screenshot of htop: