A common piece of Rust perf folklore: “mark the rare branch cold, the compiler will lay out the hot one as fall-through.” I followed that advice on a streaming indicator’s warmup path. Every wrapping indicator regressed.
![I Marked My Cold Path #[cold] and It Got 134% Slower - Dariusz Łuksza](https://luksza.org/wp-content/uploads/2026/05/cold-path-promise-vs-reality-1-1024x559.jpg)
A common piece of Rust perf folklore: “mark the rare branch cold, the compiler will lay out the hot one as fall-through.” I followed that advice on a streaming indicator’s warmup path. Every wrapping indicator regressed.