Method is_slow

crates/ffi/src/kernel.rs:2252–2254

(&self, slow_threshold: Duration)

///   positively-used refs + projection block pointers) at block
///   granularity, deduped, self-edges dropped. These are exactly the
///   edges that generate a shard's thin frontier, i.e. its ingress.
#[allow(clippy::cast_possible_truncation)] // block sizes clamped to u32::MAX
fn static_block_profile(env: &IxonEnv) -> BlockProfile {
  use rayon::prelude::*;
  let addrs: Vec<Address> =
    env.consts.iter().map(|e| e.key().clone()).collect();