Rust Performance

No change lands here that no measurement named: the profile is the entry ticket, and the codegen flags are the last five percent, not the first move. Async throughput is /async-rust; unsafe for speed is /unsafe-rust.

Measure, then change

No optimisation lands without a measurement that named it. Skipping it costs twice: the change that made nothing faster, and the change that made the code worse in exchange for nothing. A profile finds the one function that holds the time — almost never the one that looked expensive while reading.

Benchmarks that mean something

criterion for a statistical comparison against a stored baseline; divan when a lighter harness is enough. Benchmark the operation, not the setup around it.

Without it, the profiler shows addresses instead of function names: