There seems to be an issue with many of the entities creating particle systems that aren't removed when the entity is undo/removed.

This can be recreated in singleplayer and on servers. You can use "cl_show_num_particle_systems 1" in console to show the number of currently active particle systems. Spawn an entity from this mod (most of the black holes do it) and then undo it. The number of particle systems goes up but does not go down. Eventually this seems to create problems and prevent things from rendering correctly.

I have seen this with most things in the "Cosmic" tab and the swirls in the "Other" tab.