Meshes are expensive - with meshes instead of actors you don’t get any benefit at all either - such as playing a local sound when they hit the floor.
At that point, would it not be better to do a Niagara system for the shells?
They’ll cost next to nothing, can bounce around with individual simulation, and I think niagara now even hooks up into the audio so you can play a localized sound off it…
Now, its not “magic” to where it has no cost for a billion shells. But it was built to handle billions of particles, so the overall cost is much less than individual meshes or actors…