diff --git a/src/optimiser/taso.rs b/src/optimiser/taso.rs
index c9c3fed1..4e299855 100644
--- a/src/optimiser/taso.rs
+++ b/src/optimiser/taso.rs
@@ -268,7 +268,9 @@ where
         drop(tx_result);
 
         // Queue the initial circuit
-        tx_work.send((initial_circ_hash, circ.clone())).unwrap();
+        tx_work
+            .send(vec![(initial_circ_hash, circ.clone())])
+            .unwrap();
 
         // A counter of circuits seen.
         let mut circ_cnt = 1;
@@ -295,19 +297,18 @@ where
                     match msg {
                         Ok(hashed_circs) => {
                             jobs_completed += 1;
-                            for (circ_hash, circ) in hashed_circs {
+                            for (circ_hash, circ) in &hashed_circs {
                                 circ_cnt += 1;
                                 if circ_cnt % 1000 == 0 {
                                     // TODO: Add a minimum time between logs
                                     log_progress::<_,u64,usize>(log_config.progress_log.as_mut(), circ_cnt, None, &seen_hashes)
                                         .expect("Failed to write to progress log");
                                 }
-                                if seen_hashes.contains(&circ_hash) {
+                                if !seen_hashes.insert(*circ_hash) {
                                     continue;
                                 }
-                                seen_hashes.insert(circ_hash);
 
-                                let cost = (self.cost)(&circ);
+                                let cost = (self.cost)(circ);
 
                                 // Check if we got a new best circuit
                                 if cost < best_circ_cost {
@@ -315,14 +316,13 @@ where
                                     best_circ_cost = cost;
                                     log_best(best_circ_cost, log_candidates.as_mut()).unwrap();
                                 }
-
-                                // Fill the workqueue with data from pq
-                                if tx_work.send((circ_hash, circ)).is_err() {
-                                    eprintln!("All our workers panicked. Stopping optimisation.");
-                                    break;
-                                };
                                 jobs_sent += 1;
                             }
+                            // Fill the workqueue with data from pq
+                            if tx_work.send(hashed_circs).is_err() {
+                                eprintln!("All our workers panicked. Stopping optimisation.");
+                                break;
+                            };
 
                             // If there is no more data to process, we are done.
                             //
diff --git a/src/optimiser/taso/hugr_pchannel.rs b/src/optimiser/taso/hugr_pchannel.rs
index 3684e94c..c3e157cf 100644
--- a/src/optimiser/taso/hugr_pchannel.rs
+++ b/src/optimiser/taso/hugr_pchannel.rs
@@ -27,7 +27,7 @@ where
     ///
     /// Get back a channel on which to queue hugrs with their hash, and
     /// a channel on which to receive the output.    
-    pub fn init(cost_fn: C, queue_capacity: usize) -> (Sender<Item>, Receiver<Item>) {
+    pub fn init(cost_fn: C, queue_capacity: usize) -> (Sender<Vec<Item>>, Receiver<Item>) {
         let (ins, inr) = crossbeam_channel::unbounded();
         let (outs, outr) = crossbeam_channel::bounded(0);
         Self::run(inr, outs, cost_fn, queue_capacity);
@@ -36,7 +36,7 @@ where
 
     /// Run the queuer as a thread.
     fn run(
-        in_channel_orig: Receiver<(u64, Hugr)>,
+        in_channel_orig: Receiver<Vec<(u64, Hugr)>>,
         out_channel_orig: Sender<(u64, Hugr)>,
         cost_fn: C,
         queue_capacity: usize,
@@ -54,8 +54,10 @@ where
                     if pq.is_empty() {
                         // Nothing queued to go out. Wait for input.
                         match in_channel.recv() {
-                            Ok((hash, circ)) => {
-                                pq.push_with_hash_unchecked(circ, hash);
+                            Ok(new_circs) => {
+                                for (hash, circ) in new_circs {
+                                    pq.push_with_hash_unchecked(circ, hash);
+                                }
                             }
                             // The sender has closed the channel, we can stop.
                             Err(_) => break,
@@ -64,8 +66,10 @@ where
                         select! {
                             recv(in_channel) -> result => {
                                 match result {
-                                    Ok((hash, circ)) => {
-                                        pq.push_with_hash_unchecked(circ, hash);
+                                    Ok(new_circs) => {
+                                        for (hash, circ) in new_circs {
+                                            pq.push_with_hash_unchecked(circ, hash);
+                                        }
                                     }
                                     // The sender has closed the channel, we can stop.
                                     Err(_) => break,