Function spawn_blocking 

pub async fn spawn_blocking<F, R>(f: F) -> R
where
    F: FnOnce() -> R + MaybeSend + 'static,
    R: MaybeSend + 'static,

Runs CPU-bound work off the async workers so they stay schedulable.

Meant for the pairings that verify signature and decryption shares. Wasm has no blocking pool, so there the work runs inline.