A method comprising: generating a content selection graph for storing response data to be returned in response to a client request, wherein nodes of the content selection graph comprising node data representing content, each node having a node identifier, and each of the response data corresponding to a respective node identifier, and wherein edge data associated with a first node references a second node of the content selection graph, wherein the generating the content selection graph comprises: obtaining a node identifier from a build data structure, wherein the build data structure includes the node identifiers, including the obtained node identifier, to be processed for generating the content selection graph, determining, via a visited set data structure, whether the obtained node identifier has not been previously processed during the generating the content selection graph, wherein the visited set data structure represents a set of node identifiers that have already been handled, and in response to the determining that the obtained node identifier has not been previously processed, processing the obtained node identifier, including: formatting the response data that corresponds to the obtained node identifier based on client-specific information, removing the obtained node identifier from the build data structure, and adding the obtained node identifier to the visited set data structure; and preloading the content selection graph into an in-memory data storage in association with a start time at which the content selection graph becomes active. generating a content selection graph for storing response data to be returned in response to a client request, wherein nodes of the content selection graph comprising node data representing content, each node having a node identifier, and each of the response data corresponding to a respective node identifier, and wherein edge data associated with a first node references a second node of the content selection graph, wherein the generating the content selection graph comprises: obtaining a node identifier from a build data structure, wherein the build data structure includes the node identifiers, including the obtained node identifier, to be processed for generating the content selection graph, determining, via a visited set data structure, whether the obtained node identifier has not been previously processed during the generating the content selection graph, wherein the visited set data structure represents a set of node identifiers that have already been handled, and in response to the determining that the obtained node identifier has not been previously processed, processing the obtained node identifier, including: formatting the response data that corresponds to the obtained node identifier based on client-specific information, removing the obtained node identifier from the build data structure, and adding the obtained node identifier to the visited set data structure; and obtaining a node identifier from a build data structure, wherein the build data structure includes the node identifiers, including the obtained node identifier, to be processed for generating the content selection graph, determining, via a visited set data structure, whether the obtained node identifier has not been previously processed during the generating the content selection graph, wherein the visited set data structure represents a set of node identifiers that have already been handled, and in response to the determining that the obtained node identifier has not been previously processed, processing the obtained node identifier, including: formatting the response data that corresponds to the obtained node identifier based on client-specific information, removing the obtained node identifier from the build data structure, and adding the obtained node identifier to the visited set data structure; and formatting the response data that corresponds to the obtained node identifier based on client-specific information, removing the obtained node identifier from the build data structure, and adding the obtained node identifier to the visited set data structure; and preloading the content selection graph into an in-memory data storage in association with a start time at which the content selection graph becomes active.