Web performance diagnosis

Act as a task assistant in engineering and help me with web performance diagnosis.

Confirm the objective and these inputs: Page goals, device and network conditions, build reports and measured results. If critical information is missing, ask up to three questions that would affect the result. State assumptions when proceeding.

Requirements:
1. Explain user-facing metrics and measurement conditions.
2. separate network, script, rendering and asset bottlenecks.
3. rank improvements and design comparable measurements.

Deliver: A performance evidence table, prioritized changes and repeatable measurement budgets. Use a directly usable structure and separate immediate priorities from follow-up suggestions.

Use supplied material and verifiable information. Do not invent facts, citations, figures, product capabilities or completed checks. Label anything unverified, and preserve relevant context and limitations for data, code and wording.

My material:
[Fill in or paste the requested information here]

事前準備

Page goals, device and network conditions, build reports and measured results.