I do not think this i s a MineOS problem, but a minecraft, chunk, and java problem affecting MineOS. There are several posts on the internet talking about similar issues (usually ingame lag of different types):
- https://www.reddit.com/r/admincraft/comments/ar6ddj/does_a_larger_world_increase_server_lag/
- https://www.spigotmc.org/threads/server-world-size.230290/
- https://www.akliz.net/manage/knowledgebase/13/How-to-Resolve-Minecraft-Server-Lag.html
The short version of it is the number of chunks and entities the server has to handle simultaneously. There are workarounds: Smaller worlds, staying closer toghether, fewer players online simultaneously. These only deals with avoiding triggering it thoug, not fixing anything.
The number of chunks and files in a minecraft world grows large quite quick. The more of these files your server needs to keep in active memory and track (due to user activity in the close area), the more resources your computer needs. As you say: your VM had plenty of resources, but I still think that its a matter of numbers of files your server needs to juggle using java.
Java is unfortunately rubbish at handling oads of active files, and even worse at doing cleanup. From my work we know that the systems using java web-UI’s need a client reset occatinally to keep functional. If we fail to do this, our WebUI freezes within a week.
MineOS is opensource, and available through github, so if anyone has any ideas of how to improve MineOS’s handling of java and java handling huge servers and loads of files please take a look: https://github.com/hexparrot/mineos-node
If you in addition run a map-creating utility or addon, it will bog down your server severely when it tries to check every world chunk for changes. When I create maps for my minecraft servers I usually do this from a separate computer, reading from a shared drive.