dev-performance-diagnosis

Performance diagnosis workflow

Use this workflow when there is a measurable performance problem or performance-sensitive change.

Steps

1. Define the metric.

   • Latency
   • Throughput
   • Memory
   • CPU
   • I/O
   • Query time
   • Bundle size
   • Build time

2. Establish a baseline.

   • Use comparable commands, traces, profiler output, query plans, browser metrics, or logs.
   • Record environment and input size.

3. Form hypotheses.

   • Algorithm or data structure
   • Database/index/query
   • Network/API chatter
   • Cache behavior
   • Rendering or bundle cost
   • Build/tooling overhead
   • Memory leak or object retention

4. Test one change at a time.

   • Keep correctness tests in place.
   • Measure before/after.
   • Prefer targeted fixes over architecture replacement.

5. Confirm no regression.

   • Run relevant correctness checks.
   • Check edge cases and resource limits.
   • State noise or uncertainty in the measurement.

Output

Return:

1. Metric and baseline
2. Bottleneck evidence
3. Change or recommendation
4. Before/after result
5. Remaining uncertainty

Do not

• Do not claim speedups without measurement.
• Do not optimize code that is not on the measured path.
• Do not trade correctness, security, or data integrity for speed.