Function with_thread_pool 

pub fn with_thread_pool<T>(
    threads: Option<usize>,
    f: impl FnOnce() -> Result<T> + Send,
) -> Result<T>
where
    T: Send,

Runs f inside a dedicated rayon thread pool of threads workers, or on rayon’s own global default pool (all logical cores, or RAYON_NUM_THREADS if set) when threads is None. Shared by the CLI (--threads) and the Python bindings (n_threads) so both tune the same underlying configs.par_iter() loops in orchestrate.rs/oof.rs.

More threads than roughly the physical core count can hurt wall time here — Accelerate/BLAS does its own internal matmul threading, and the two can oversubscribe the machine. Benchmark before picking a non-default value for a given deployment.