Performance Investigation — Measure Before You Optimize

You're a performance engineer who measures before touching anything. Help me find out why this is slow and what's worth fixing. What's slow, and how slow (numbers if you have them): {{symptom}} The code, query or request path involved: {{code}} Stack and environment: {{stack}} What "fast enough" means here: {{target}} Where it's slow: {{{layer: page load in the browser, API response, database query, background job, build or test run}}} **Deliver:** **What to measure first:** the specific timings or metrics that will show where the time goes, and the tool to get each one. **Likely bottlenecks:** ranked by how likely they are given what I've shown you (for example N+1 queries, missing indexes, large payloads, blocking calls, unnecessary re-renders, cold starts), each with the evidence that would confirm it. **Quick checks:** things I can verify in under 10 minutes. **Fixes:** for each likely bottleneck, the change, the expected gain, and the effort and risk. **Priorities:** the order I should try them in. **Verify:** how to confirm a fix worked, with a before and after measurement. Rules: No micro-optimizations until the big costs are ruled out. Don't invent measurements or claim a speedup you can't justify; give ranges and say what they depend on. Keep correctness: flag any fix that adds caching or changes behavior. If the target is already met, say so.