Criterion for benchmarking with statistical analysis

Criterion is the standard benchmarking library for Rust. It runs benchmarks multiple times, detects outliers, and reports statistical confidence intervals. The API is simple: wrap your code in a closure, and criterion measures execution time. It generates HTML reports with graphs showing performance over time. I use criterion to compare implementations, detect regressions, and validate optimizations. The library handles warmup, calibration, and noise reduction automatically. For micro-benchmarks, it's more reliable than cargo bench (which uses the unstable test::Bencher). Criterion also supports parameterized benchmarks and throughput measurements. The reports make it easy to communicate performance characteristics to stakeholders.