Optimization of network-transferred multi-card content items

One or more storage media storing instructions which, when executed by the one or more processors, cause:

• storing, based on input from a content provider, a content delivery campaign that comprises a content item that comprises a plurality of cards, wherein content of each card of the plurality of cards originates from the content provider;
• initiating a first content item selection event that involves a first plurality of content delivery campaigns that includes the content delivery campaign;
• as part of the first content item selection event, selecting the content delivery campaign;
• causing the content item that comprises the plurality of cards to be transmitted to a first computing device of a first user, wherein the plurality of cards have a first card configuration;
• identifying one more events that are associated with the first computing device displaying at least one card of the plurality of cards;
• wherein the one or more events includes a first event that indicates that a first card in the plurality of cards was presented on the first computing device;
• wherein the first event indicates a position of the first card relative to other cards in the plurality of cards;
• based on the plurality of events, determining a second card configuration, of the plurality of cards, that is different than the first card configuration;
• initiating a second content item selection event that involves a second plurality of content delivery campaigns that includes the content delivery campaign;
• as part of the second content item selection event, selecting the content delivery campaign;
• causing the content item that comprises the plurality of cards to be transmitted to a second computing device of a second user, wherein the plurality of cards have the second card configuration.