1. A system comprising: one or more server computing devices comprising one or more processors and one or more computer storage media, the one or more server computing devices programmed to at least: identify, based at least on first request analysis information, one or more metrics regarding execution of a request for a content page hosted by a content server, wherein the one or more metrics indicate information associated with network or user computing device performance; generate a plurality of background request instructions based on the identified one or more metrics, wherein each of the background request instructions comprise one or more instructions to provide requests for the content page associated with a network address to one or more content servers of a plurality of content servers storing the content page; transmit at least one of the plurality of the background request instructions to each of a plurality of user computing devices; receive, from one or more of the plurality of user computing devices, second request analysis information, the second request analysis information reflecting the one or more metrics associated with execution of the generated background requests; determine, using the received second request analysis information, characteristics associated with user computing devices indicating that, in response to user requests, user computing devices associated with the determined characteristics are to provide future requests for the content page to a particular content server of the plurality of content servers storing the content page; and provide, to the plurality of user computing devices, information indicating the determined characteristics.