Perf Profiler

This profiler analyzes performance across three layers: code complexity (spots O(n²) loops that should be hash tables), database queries (catches N+1 problems and missing indexes), and network calls (suggests request batching and caching). It outputs a tiered report with critical bottlenecks flagged red if they impact over 50% of performance, plus estimated before/after metrics. Honestly most useful when you know something's slow but can't pinpoint where, since it covers the usual suspects systematically. The concrete optimization suggestions with complexity comparisons are more actionable than just profiler flamegraphs, though you'll still need to validate the timing estimates yourself.