Hey there,
I’m very new here so I’m sorry for any faults in advance.
I have the same problem without using any “acitvate” or “deactivate” features.
I have a simple level with a looped niagara actor in it.
The fps drops every time the niagara particles are shown and the loop is active.
It seems to me that the Niagara Plugin is source of the Problem.
Thank you for any ideas or hints.