Significant application performance degradation when making a module public

I've encountered an unexpected and significant performance degradation in my application when changing a module's visibility from private to public. This behavior seems counterintuitive and potentially indicates a compiler optimization issue or an unexpected interaction between module visibility and performance.

my code:

mod black:

source: https://github.com/hayden4r4/blackscholes-rust/blob/master/src/lets_be_rational/mod.rs#L8
benches: https://github.com/hayden4r4/blackscholes-rust/blob/master/benches/black.rs

Current behavior

When the black module is made public, the overall application performance degrades by approximately 50%.

Expected

Changing a module's visibility should not have a significant impact on the application's overall performance. We would expect minimal to no performance change when modifying module visibility.

Environment

Rust version: 1.80.0 (051478957 2024-07-21)
Cargo version: 1.80.0 (376290515 2024-07-16)
os: macos m1 max

Anyone may know where is the bug/problem/challange?

Start with src/lets_be_rational/mod.rs at the cited module declaration and the benches/black.rs benchmark. Run the benchmark with the module private and public on the stated Rust and macOS environment, then inspect compiler output or profiling data to isolate the cause. Done means identifying whether this is a compiler optimization issue and documenting a reproducible result or fix direction.