!! A usual beginner's mistake is extending the entities' bounding box all the way to its feet and then apply gravity for pressing the entity against the ground. This is not only slow due to the permanent collisions with the ground, it will also cause the entity to get stuck in any little crack in the floor, and prevent it from ascending stairs or slopes. Rather, use c_trace for keeping the entities' bounding box at a distance from the ground, and apply gravity only above that distance. See the example below for a simple movement function.