If you have set a sphere to 500 Segments, which results in 200,000 “polygons” each of it needs to be calculated with the Cloners output in terms of collision, each frame. I’m not surprised that it is slow.
Lower that number and use a Subdivision Surface to get close to the shape you are after. Anything else is mainly based on the computing power you have. I’m not certain if a polygon sphere (made editable) and a Point Cache would really help here, that is up to you to test.
Have you tried to get your result with Volume [R20}
All the best