SBCL needs a relatively large amount of memory to start with, but beyond that it doesn't require much. I run a few small services written in Common Lisp. Instead of running a separate process for every one of them I run a single SBCL process and run each service in a different thread.

This has some downsides: Firstly they run in the same address space, so global state is shared and serious bugs can affect another service. Secondly they run as a single systemd service, so they're not easy to manage individually. Still I've found it to work quite nicely for things that are simple and don't really need attention.