Particular embodiments arrange a plurality of objects in a hierarchy, the hierarchy having one or more layers and each layer having at least one of the objects; display a portion of a sequence of first objects on a screen of a user device, the sequence of first objects all belong to a first layer in the hierarchy, each first object having as its children one or more second objects belonging to a second layer immediately below the first layer in the hierarchy; in response to a user scrolling through the sequence of first objects, estimate which specific first object in the sequence the user is likely to be viewing at a predetermined time in the future based on an acceleration of the user scrolling through the sequence of first objects; and preload the second objects that are children of the specific first object.