Running benchmarks is easy (but requires a nightly compiler):
cargo bench # In a few cases, nightly features may use different code paths: cargo bench --features=nightly
A lot of code in Rand is performance sensitive, most of it is expected to be
used in hot loops in some libraries/applications. If you change code in
rand_core, in PRNG crates, or in the
(especially when an 'obvious cleanup'), make sure the benchmarks do not regress.
Please report before-and-after results for any affected benchmarks. If you are optimising something previously not benchmarked, please add new benchmarks first, then add your changes in a separate commit (to make before-and-after benchmarking easy).