You are probably right that having a slower processing speed isn’t an advantage overall, but being able to perceive patterns like this may be advantageous in some situations.

Maybe the slower processing speed is the cost of better processing power? Kinda like the tradeoff between high torque and high speed for gearboxes.

Some tribes use psychedelics for hunting, and others that use psychedelics for introspection: maybe they are perceiving something that we ignore during normal processing modes.