How much speed should a reining horse show in fast circles?

A reining horse in the large fast circle should show enough speed to demonstrate genuine athleticism and create a visible, obvious contrast with the small slow circle — because the contrast between the two sizes is what the maneuver is designed to test, and if the fast circle does not look meaningfully faster than the slow one the horse is not demonstrating the rate and collection the pattern requires. The horse should appear to be galloping with purpose and forward energy, covering ground efficiently with each stride rather than taking many short quick steps to produce its speed. At the same time, speed without guide, balance, or cadence can hurt the score as much as insufficient speed, because a horse that runs out of the rider's control, loses its circle shape, breaks down in cadence, or requires significant management to stay in the correct lane is demonstrating lack of training rather than athleticism. The horse must look fast but still rideable — a judge who watches the fast circle should see a horse that is clearly moving out with energy while the rider appears to be guiding with light, subtle contact rather than hauling, pushing, or managing a horse that is on the edge of its training. The correct amount of speed is therefore not a specific pace but a level at which the horse can maintain guide, shape, cadence, and balance while showing obvious forward energy. Horses that are pushed faster than their training and balance currently support will show the excess through drifting circles, lead changes, loss of cadence, or difficulty transitioning back to the slow circle. Building speed gradually onto a foundation of correct circle shape and guide produces a horse that can eventually gallop at a competitive pace while staying soft and controlled.