Hello,
I have done a preliminary investigation. Very nice test case for benchmarking btw!
So Adorns are really slow, they are not meant to be used in the way they are used in the test case. The mesh parts, I expected it to be a little costly while adding parts, due to the way that works internally. But I was surprised to see the cost continues after stopping the benchmark. I debugged this a bit and I will have to continue debugging it tomorrow or so, it seems to think the parts are dynamic, when they are not… this is what triggers the update.
I think what’s more important at this point is trying to understand your use case. There is no specialized solution for rendering many many tiny parts. This is also largely true for other game engines. So we should better understand your use case, so we can provide some guidance on how to make this work well within Roblox.