Project looks impressive. Hope you succeed in getting the performance you want whichever method you use 
Unless you have already tried these they may be worth a read
https://doc.babylonjs.com/how_to/solid_particles#sps-management
https://doc.babylonjs.com/how_to/optimizing_your_scene
Also I see you have 40 meshes in the SPS scene are you building just one SPS?