Pereskiopsis Spathulata will put on 10cm+ in a week when grown in favourable conditions. Which is warmth and humidity with loads and loads of nutes. The thing is it don't really look like a cacti.
All the grafting stocks grow fast. Trichocereus, Hylocereus, Myrtillocactus, Opuntia, Cereus (most).
There are heaps