Features are disclosed for automatically generating content requests and recording metrics and other information about execution of the requests. The requests can be background requests, executed by user computing devices during idle periods and without any user initiation. The background requests may be browser requests for content pages. Metrics and other information about execution of the requests may be recorded during execution of the background requests and reported to a performance analysis system. Instructions to execute background requests can be generated so as to develop a data set, such as a data set for analyzing request execution performance.