A system can be provided for dynamically serving a content file. A content object request function can receive a request for a webpage defined by the content file, the content file including a plurality of embedded or referenced content objects, at least one of the plurality of content objects including a Javascript. A content-file modifier can modify the content file to include instructions to generate reports comprising information relating to invocation of stubs. A report receiver can receive reports from the end user system, and an object usage analyzer quantifes usage of each of the stubs. An object prioritizor can prioritize the plurality of content objects based on the analysis, the prioritization including an identification of at least one high-priority content object. An object injector can modify the content file such that the high-priority content object automatically loads upon rendering of the content file.