I've just tried out a bit with .NET Core 2.2. Baseline of the non-multithreaded variant on my machine: 1m56s Making Vector3 a struct: 1m3s Making Vector3 a r

I've just tried out a bit with .NET Core 2.2. Baseline of the non-multithreaded variant on my machine: 1m56s Making Vector3 a struct: 1m3s Making Vector3 a readonly struct: 1m1s Making Hit and Ray a struct: 1m26s Will test more tomorrow, I guess, but the most obvious change already yields a 2× speedup. This was also without any profiling, so I don't even know what I did there.