Amazon has open-sourced its Krakatoa VFX particle renderer and the associated shader system. Appears to be Maya focused, so I guess they were/are using this for the Amazon TV VFX. The VFX world has many particle-generators / particle-renderers by now, but this one is said to be especially “fast”. That’s the only claim made for it, at least on the GitHub. Still, if you were looking to plug a fast particle system into Poser 13, I see lots of .PY scripts in the Krakatoa GitHub and it might be something to consider.