parking_lot provides drop-in replacements for Mutex, RwLock, and Condvar that are faster and smaller than std::sync. They use more efficient parking/unparking and don't poison on panic. I use parking_lot::Mutex in hot paths where lock contention matters. The API is nearly identical to the standard library, so switching is easy. The main difference is that parking_lot doesn't return LockResult, so you don't need .unwrap(). For production services with high concurrency, parking_lot can noticeably improve throughput. It's a simple dependency change that often pays off.