Why not have "magic" that increase your movement speed, and add it as a mount.
Let it be sparkles around your feet or your body and call it a day.
I'm not the type for huge mounts, like the Snow Owl or the Hydra, or the Treant, that take up half the screen. That, and I want to see my pet while I run. I don't really care too much for mounts. I just use them because you move faster.