In my experience, the lounge leaks a lot of memory. After about 30 days of running, it used 8GB and the shared hoster I put it on killed it. Would definitely not recommend as bouncer.
If you have many users/channels, you can tweak `maxHistory`, which controls how many messages are kept in memory per channel for the backlog. That's where most of the memory usage comes from.
https://thelounge.chat/docs/configuration#maxhistory