Block Loading Problem

Hello,
I added Galacticraft mod to the server.
For example, when the player is not in a world, the world will still be loaded 256 blocks.
However, this problem has not arisen in the [World].
I don’t want him to uninstall the world, but to control the loaded blocks without players.
For example, when there are no players, only 10 blocks around span are loaded?
Can I use a sponge to modify the configuration file?
Thank you very much.
I’m sorry. My mother tongue is not English, I hope I can express clearly.

Well, I’ve solved this kind of problem myself.