A method and system for detecting slow page load is provided. An example system comprises a page request detector, a session state information detector, a throughput calculator, a response builder, and a communications module. The page request detector may be configured to receive a request for a web page. The session state information detector may be configured to determine that the request does not include session state information. The throughput calculator may be configured to calculate a throughput value associated with the network connection between the client system and the server. The response builder may be configured to build an updated data packet by including, in the data packet, the throughput value and an instruction to store the throughput value on the client as session state information. The communications module may be configured to communicate the updated data packet to the client system.