I assume a significant amount of openHAB instances are running on single board computers.
These have usually a limited set of memory especially the Raspberry Pi 3 based.

For me openHAB 4.0.x runs successfully with some modifications on a Raspi 3a+ (512 MB).
I would like to share these to upstream these changes / find some other improvements.

1. Set -Dxtext.qn.interning=true or call QualifiedNameInterning#enable() to intern the strings inside the QualifiedName instances.
   This will remove a lot of Strings (~50%) from memory and could be exposed to the UI and the default setting could be enabled.

2. Disable Use IPv6 in Network Settings of openHAB to get rid of a second jmDNS instance.
   This might be a good default value for most users?

3. Set -Xss1024k, this will half the thread stack size from the 2048k default
   This is a more advanced topic but could be documented somewhere.
   openHAB is using 200+ threads and this has quite an impact

4. Set -XX:+UseG1GC and -XX:+UseStringDeduplication to enable string deduplication on GC level

Do you think memory usage is an issue at all or are most of the users currently running a SBC with 2+gb RAM?
Are there further tips and tricks to improve the memory consumption?

Your Environment

• Version used: openHAB 4.0.x
• Environment name and version: Raspi 3a+
• Operating System and version: Raspbian Bookworm