Got back to my CPU RayTracer (single-threaded, no SIMD) applying a very simplified "Acceleration Structure", and got a MASSIVE performace boost. Not a BVH or anything (yet), but works very well for spheres 😇 Debug-mode shows how it works: Just doing an orthographic projection of each sphere onto a projection plane set at a distance of the sphere's center (appropriately scaled, accounting for the focal length), then taking a screen-space bounding-rectangle. Additionally, pre-emptively filtering-out spheres that can be easilly rejected as being out of view. The HUD show's how many "active" spheres are being considered, as well as what overall percentage of the screen's pixels get a ray traced for them 😁 With these kind of FPSes, gonna start doing some shading now.