Aglet

How to verify a slow first load improvement with matched traces

Verification asks whether the page became usable sooner under comparable conditions and whether the change preserved the route's work. Use a matched baseline, repeat enough captures to see variation, and check both cold and returning sessions. Treat an inconclusive sample as a result that needs more observation.

Check whether the outcome improved

  1. Define a matched baseline and readiness mark

    Select the prior trace or an unchanged build with the same route, account shape, viewport, and network profile. Define readiness as the actual first action becoming usable, not merely a paint event. Record server start, first byte, document completion, and readiness for every run.

  2. Repeat cold and returning captures

    Run several captures with cleared resources and several with normal cache state, keeping inputs fixed. Compare medians or distributions rather than the fastest run. Note any changes in request order, response errors, missing content, or client exceptions that could make a shorter trace misleading.

  3. Check neighboring routes and first action

    Open a related route and exercise the first meaningful control after the page appears. Confirm that navigation, form submission, accessibility announcements, and loading recovery still work. Inspect payload and asset changes for unexpected cost moved into a later interaction.

What to carry forward

Report verified improvement, no meaningful change, regression, or inconclusive evidence. Include the matched conditions, readiness comparison, cache state, and side-effect checks. Verification is complete only when the observed result supports the intended user action and the remaining uncertainty is explicit enough for a follow-up decision.

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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