Increasing the spawn rate of a CPU particle sim will cause a memory leak in the vertex buffer.
The vertex buffer memory usage will not recover from the spike after increasing the spawn rate, even after closing the Niagara editor and deleting the system.
Memory usage from the increases particle count should recover when the number of particles are reduced, and the systems are deleted/closed. GPU sims behave in the expected way.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-77393 in the post.