Sled: Embedded Database Written in Rust
Apparently if you're on Windows you don't deserve performance:    #[cfg(windows)]
    const MAX_THREADS: usize = 16;


    #[cfg(not(windows))]
    const MAX_THREADS: usize = 128;

From: https://github.com/spacejam/sled/blob/bf37bd120fbf62f78408e0...