Fast Thread Locals In Rust Oct 3, 2020 Rust thread-locals are slower than they could be. This is because they violate zero-cost abstraction principle, specifically the “you don’t pay for what you don’t use” part. Rust’s thread-local implementation( 1, 2 ) comes with built-in support for laziness — thread locals are initialized on the first access. Sometimes this overhead is a big deal, as thread l