Detecting a collider in 3D space.

Simple question; what is the simplest and most performance-efficient method for determining whether a collider exists at a specific point in 3D space?

I will need to do this maybe ~8-16 times per active rigidbody in my scene, per FixedUpdate.

You can loop over all of your colliders and check Bounds.Contains.

To get more performance, you could somehow partition your colliders so that the search space is as small as possible. Managing this will probably take more CPU cycles than it’s worth if you have moving colliders.