Extensible dynamic performance instrumentation of pages

In computing environment including a web server and a web client, a method of gathering performance information with respect to delivering web resources as perceived by a user at the web client the method comprising:

• at a server, receiving a request for a web page;
• as a result of receiving the request, sending an HTML document, the HTML document comprising references to a plurality of web page resources used to render a web page;
• and
• as a result of receiving the request sending a first set of executable instructions injected into the HTML document, the first set of executable instructions including a list of a plurality of resources, that is a subset of the web page resources, that are required to be at least one of downloaded to or rendered at the client for the web page to be considered loaded at the client, and configured to determine when each individual resource in the required resources have been be at least one of downloaded to or rendered at the client, and to determine a length of time associated with at least one of downloading to or rendering at the client the resources in the plurality of resources.

One or more physical computer readable storage media comprising computer executable instructions that when executed by a processor are configured to perform the following:

• receive a request for a web page;
• as a result of receiving the request, sending an HTML document, the HTML document comprising references to a plurality of web page resources used to render a web page;
• and
• as a result of receiving the request send a first set of executable instructions injected into the HTML document, the first set of executable instructions including a list of a plurality of resources, that is a subset of the web page resources, that are required to be at least one of downloaded to or rendered at the client for the web page to be considered loaded at the client, and configured to determine when each individual resource in the required resources have been be at least one of downloaded to or rendered at the client, and to determine a length of time associated with at least one of downloading to or rendering at the client the resources in the plurality of resources.