Delivering a continuous feed of content items to a client device

An online system provides a continuous feed of content items to a client device. The online system maintains an ordered set of ranked content items for sending to the client device. The online system receives requests from the client device for content items and selects a subset from an ordered set of ranked content items in response to each request. The number of content items in the subset may be based on factors such as the network connection strength of the client device. The client device re-ranks content items received from the online system based on information received during a given session. The session information may indicate the types of content items viewed during the given session, or the speed at which the user is viewing content items during the given session.