Comment by dvdkon
Fine, then let's not bother with anti-cheat at all, since an aimbot can work by just filming the screen and sending HID events over USB. Anti-cheat is like DRM: You have to make do with a compromise.
Hundreds of thousands of raycasts per second sounds doable to me, but couldn't you just use a GPU and some simplified level geometry? That ought to scale well enough. It's not free or perfect (knowing the position of a hand a cheat will be able to estimate where the head is anyway), but that's not the goal, right?
There is a video of DYI aimbot of using a camera and sending electrical impulses into his arm to make him do certain adjustments. It's a bit hit and miss but seems refineable.
It's cat and mouse game.