Aglet

How to investigate slow first loads with a timing brief

A useful slow-load investigation turns a waterfall into a narrow engineering brief. Follow one route from request receipt through HTML, assets, data hydration, and interactive readiness. Separate measured intervals from hypotheses, then test one boundary at a time so improvements remain attributable.

Build a useful investigation brief

  1. Break the server-to-interactive timeline

    Align request logs, response timing, browser navigation marks, and readiness events on one clock where possible. Measure controller or handler work, database calls, template rendering, response transfer, script evaluation, and image decoding. Record missing timestamps instead of filling gaps with assumptions.

  2. Inspect transfer and parse cost

    List the largest responses and the scripts or stylesheets that delay usable controls. Check whether duplicate assets, unneeded route data, or oversized images appear before the first action. Compare compressed and decoded sizes, and note whether caching changes the sequence for returning sessions.

  3. Test one candidate change in isolation

    Choose a single bounded experiment, such as deferring a noncritical module or reducing initial query data. Re-run the same route, state, and network profile, then compare each timeline boundary. Keep the original trace beside the experiment so a faster total cannot hide a new bottleneck.

What to carry forward

Deliver an evidence-backed brief with the first expensive interval, its supporting measurements, one tested change, and unresolved alternatives. A hypothesis stays labeled as such until a controlled comparison moves it toward confidence. Stop when the next implementation step has a clear input, owner, and observable outcome.

Keep the decision with the work.

Use a Work Item in Aglet to record the problem, the evidence you have, and the next decision. Add an owner and priority, then keep updates in the discussion so the next person can follow the reasoning.

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