A web server monitors and receives measurements as to how long a client device takes to load or display individual items after a user first requests a web page containing the items. The measurements may be based on a duration that begins at a time between a user's navigation request and network browser's transmission of a request for a new web page. The recorded measurements received by the web server may include measurements relating to the latency experienced by the user in loading a particular item of content for a web page, such as an image, or may include the latency experienced by the user in loading an entire web page. One or more components used by the network browser, such as a network browser plug-in and or scripting language embedded in a web page, may provide one or more routines for measuring and reporting the latencies experienced by the user.