Here is another example that shows the issue I’m dealing with.
The PG creates an expandable SPS with 10 boxes. Every half second a box is positioned. When the last box in the SPS is positioned, 10 more boxes are added to the SPS.
Changing the code to update all particles only when expanding improves things. The first 10 particles are still having issues, though. https://playground.babylonjs.com/#X1T859#12