Gelding a horse does not increase its maximum potential speed. The genetic makeup of how fast a horse is capable of running can not be changed. When gelding improves a horses speed it is just helping it to get to its maximum speed more quickly by improving its focus.

How does gelding affect a horse?

A male horse is often gelded to make him better-behaved and easier to control. Gelding can also remove lower-quality animals from the gene pool. To allow only the finest animals to breed on, while preserving adequate genetic diversity, only a small percentage of all male horses should remain stallions.

Does gelding improve behavior?

Bras delivered an important caveat — gelding only works to improve behavior if the horse is fairly young at the time of the procedure. “It depends on a horse's age. There are two things — learned behavior, and a reaction to hormones,” said Bras.