A method, program and system for service time analysis in a computer network are provided. The invention comprises receiving a request from a network client machine and recording the initial time value for the request. The request is forwarded to an origin server. The response stream from the origin server is instrumented with the initial time value (plus the service time taken for the origin server to respond) and sent back to the client machine. A uniform resource identifier (URI) request (e.g. images) is received from the client machine, and the service time for completing the URI is recorded. The URI request is forwarded to the origin server, and the service time value for the URI is updated to reflect the origin server response. The URI response from the origin server is then sent to the client machine.