diff --git a/orch8-engine/src/scheduler.rs b/orch8-engine/src/scheduler.rs
index 837c0e4c..5878a0d0 100644
--- a/orch8-engine/src/scheduler.rs
+++ b/orch8-engine/src/scheduler.rs
@@ -1522,13 +1522,19 @@ async fn emit_sla_alerts(
         .map(|c| (c.instance_id, &c.block_id))
         .collect();
     let existing = ctx.storage.get_block_outputs_batch(&keys).await?;
-    let mut existing_ref = std::collections::HashSet::with_capacity(existing.len());
-    for k in existing.keys() {
-        existing_ref.insert((&k.0, &k.1));
-    }
+
+    // Performance: Sorting keys and using binary search avoids
+    // the allocation and hashing overhead of building a HashSet for
+    // exclusion checking on the execution hot path.
+    let mut existing_keys: Vec<(&InstanceId, &BlockId)> =
+        existing.keys().map(|(iid, bid)| (iid, bid)).collect();
+    existing_keys.sort_unstable();
 
     for c in candidates {
-        if existing_ref.contains(&(&c.instance_id, &c.block_id)) {
+        if existing_keys
+            .binary_search(&(&c.instance_id, &c.block_id))
+            .is_ok()
+        {
             continue;
         }
         // Persist the sentinel BEFORE emitting so a crash mid-emit cannot
diff --git a/orch8-types/src/ids.rs b/orch8-types/src/ids.rs
index 5463e8ea..c325d76f 100644
--- a/orch8-types/src/ids.rs
+++ b/orch8-types/src/ids.rs
@@ -5,7 +5,20 @@ use uuid::Uuid;
 /// Newtype wrappers prevent mixing up UUIDs at compile time.
 /// Zero cost at runtime (transparent newtypes).
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Serialize, Deserialize, sqlx::Type, ToSchema)]
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    Hash,
+    Serialize,
+    Deserialize,
+    sqlx::Type,
+    ToSchema,
+)]
 #[sqlx(transparent)]
 pub struct InstanceId(Uuid);