Pretty neat. I'm wondering why this improves performance so much. I think the idea is that you restrict the problem so that bullets don't collide with each other so you don't need to check the interaction between pairs of bullets which makes the complexity of collisions O(n) instead of O(n^2) where n is the number of bullets. The main drawback of course is that bullets can't collide with each other.
I wonder if it would be possible to use physics layers to implement that like if I set the bullet at layer 1 but not at mask 1, then bullets wouldn't check collisions with each other.
Thanks for the devlog! It might help me with my project in the future!