'multiple objects collision' what exactly do u mean by that?

The sphere can collide with the fractal at multiple points.
But in the demo there is just the fractal and the sphere.

The significant performance hit when calculating collision detection for a very large number of objects at the same time, like the falling tower in the video

no, definitely not... A sphere is the easiest thing *by far* to do collisions for.
The cool thing here is that hes doing collisions with a fractal and one sphere.

I have no idea is there any in-software way to optimize lots and lots of colliders.
Not that I know of, but maybe there is some clever bastard working on that somewhere too.

Modern physics engines do as good as they can on that front already afaik.

Bawbag, did your world implode after you figured out I
wasn't Orcs?