The Cactus Knife is an EPICHoe, specialised for farming Cactus. It can break Cactus instantly, and increases the player's ✦ Speed Cap by 100 while held on ⏣ The Garden.
Since vanilla Minecraft does not provide a way to insta-break cactus in survival mode, the Cactus Knife's ability is implemented server-side, meaning this means there is a one tick delay before the cactus breaks. Therefore, you cannot break multiple layers of cactus at once without losing efficiency.
This means that maximum efficiency when farming cactus requires 464✦ Speed.