Performance Profiler

Performance Profiler

Systematic performance profiling for Node.js, Python, and Go applications. Identifies CPU bottlenecks with flamegraphs, detects memory leaks with heap snapshots, analyzes bundle sizes, optimizes database queries, detects N+1 patterns, and runs load tests with k6 and Artillery. Enforces a measure-first methodology: establish baseline, identify bottleneck, fix, and verify improvement.

Golden Rule — Measure First: Profile → Confirm bottleneck → Fix → Measure again → Verify improvement. Every optimization needs baseline metrics, profiler evidence, the fix, post-fix metrics, and a delta. Full rule in references/cpu-and-memory-profiling.md.

Core Capabilities

• CPU profiling — Clinic.js/V8 flamegraphs (Node), py-spy/cProfile/scalene (Python), pprof (Go), Chrome DevTools (browser).
• Memory profiling — heap snapshots and before/after comparison, GC pressure analysis, leak detection, retained object graphs.
• Database optimization — EXPLAIN ANALYZE plan reading, N+1 detection and batching, slow query logs, missing-index identification, connection pool sizing.
• Bundle analysis — webpack/Next.js analyzers, tree-shaking, dynamic imports, heavy dependency identification.
• Load testing — k6 ramp-up scripts, SLA threshold enforcement in CI, P50/P95/P99 latency tracking, concurrent user simulation.

When to Use

• App is slow and you do not know where the bottleneck is.
• P99 latency exceeds SLA before a release.
• Memory usage grows over time (suspected leak).
• Bundle size increased after adding dependencies.
• Preparing for a traffic spike (load test before launch).
• Database queries taking >100ms, or verifying no regressions after a dependency upgrade.

Clarify First

Before profiling, confirm these inputs. If any is unknown or vague, ASK — do not assume:

• Runtime & symptom — Node / Python / Go and CPU / memory / bundle / query / load-spike (selects the profiler and toolchain)
• Baseline + SLA target — current numbers and the P95/P99 (or size) threshold to beat (measure-first needs both to verify a delta)
• Environment — local / staging / prod determines the safe profiling method and whether load testing is allowed

Stop rule: ask only the 2-3 that most change the output. If the user says "just draft it," proceed and list your assumptions at the top of the artifact.

Tools