diff --git a/CHANGES.md b/CHANGES.md
index 1a6083f03f..0ee620fca2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -28,8 +28,9 @@ To be released.
 
 ### Behavioral changes
 
- -  Improved performance of `Swarm<T>` by multiplexing response and
-    broadcast.  [[#858], [#859]]
+ -  Improved performance of `Swarm<T>`.
+     -  Multiplexed response and broadcast.  [[#858], [#859]]
+     -  Reduced internal delays.  [[#871], [#879]]
  -  `Transaction<T>.Create()`, `Transaction<T>.EvaluateActions()` and
     `Transaction<T>.EvaluateActionsGradually()` no longer throw
     `UnexpectedlyTerminatedActionException` directly. Instead, it records
@@ -48,8 +49,10 @@ To be released.
 [#859]: https://github.com/planetarium/libplanet/pull/859
 [#860]: https://github.com/planetarium/libplanet/issues/860
 [#868]: https://github.com/planetarium/libplanet/pull/868
+[#871]: https://github.com/planetarium/libplanet/issues/871
 [#875]: https://github.com/planetarium/libplanet/pull/875
 [#878]: https://github.com/planetarium/libplanet/pull/878
+[#879]: https://github.com/planetarium/libplanet/pull/879
 
 
 Version 0.9.2
diff --git a/Libplanet/Net/NetMQTransport.cs b/Libplanet/Net/NetMQTransport.cs
index 80d66a0524..2bdc1c3f36 100644
--- a/Libplanet/Net/NetMQTransport.cs
+++ b/Libplanet/Net/NetMQTransport.cs
@@ -431,10 +431,8 @@ public void Dispose()
 
         public Task WaitForRunningAsync() => _runningEvent.Task;
 
-        public async Task SendMessageAsync(BoundPeer peer, Message message)
-        {
-            await SendMessageWithReplyAsync(peer, message, TimeSpan.FromSeconds(3), 0);
-        }
+        public Task SendMessageAsync(BoundPeer peer, Message message)
+            => SendMessageWithReplyAsync(peer, message, TimeSpan.FromSeconds(3), 0);
 
         public async Task<Message> SendMessageWithReplyAsync(
             BoundPeer peer,
@@ -490,18 +488,25 @@ await _requests.AddAsync(
                     Interlocked.Read(ref _requestCount)
                 );
 
-                var reply = (await tcs.Task).ToList();
-                foreach (var msg in reply)
+                if (expectedResponses > 0)
                 {
-                    MessageHistory.Enqueue(msg);
-                }
+                    var reply = (await tcs.Task).ToList();
+                    foreach (var msg in reply)
+                    {
+                        MessageHistory.Enqueue(msg);
+                    }
 
-                const string logMsg =
-                    "Received {ReplyMessageCount} reply messages to {RequestId} " +
-                    "from {PeerAddress}: {ReplyMessages}.";
-                _logger.Debug(logMsg, reply.Count, reqId, peer.Address, reply);
+                    const string logMsg =
+                        "Received {ReplyMessageCount} reply messages to {RequestId} " +
+                        "from {PeerAddress}: {ReplyMessages}.";
+                    _logger.Debug(logMsg, reply.Count, reqId, peer.Address, reply);
 
-                return reply;
+                    return reply;
+                }
+                else
+                {
+                    return new Message[0];
+                }
             }
             catch (DifferentAppProtocolVersionException e)
             {
@@ -621,28 +626,32 @@ private void DoBroadcast(object sender, NetMQQueueEventArgs<(Address?, Message)>
             (Address? except, Message msg) = e.Queue.Dequeue();
 
             // FIXME Should replace with PUB/SUB model.
-            try
-            {
-                var peers = Protocol.PeersToBroadcast(except).ToList();
-                _logger.Debug($"Broadcasting message [{msg}]");
-                _logger.Debug($"Peers to broadcast : {peers.Count}");
-                Parallel.ForEach(peers, async peer =>
-                {
-                    await SendMessageAsync(peer, msg);
-                });
+            List<BoundPeer> peers = Protocol.PeersToBroadcast(except).ToList();
+            _logger.Debug("Broadcasting message: {Message}", msg);
+            _logger.Debug("Peers to broadcast: {PeersCount}", peers.Count);
 
-                _logger.Debug($"[{msg}] broadcasting completed.");
-            }
-            catch (TimeoutException ex)
-            {
-                _logger.Error(ex, $"TimeoutException occurred during {nameof(DoBroadcast)}().");
-            }
-            catch (Exception ex)
+            foreach (BoundPeer peer in peers)
             {
-                _logger.Error(
-                    ex,
-                    $"An unexpected exception occurred during {nameof(DoBroadcast)}()."
-                );
+                _ = SendMessageAsync(peer, msg)
+                    .ContinueWith(t =>
+                    {
+                        const string fname = nameof(DoBroadcast);
+                        switch (t.Exception?.InnerException)
+                        {
+                            case TimeoutException te:
+                                _logger.Error(
+                                    te,
+                                    $"TimeoutException occurred during {fname}()."
+                                );
+                                break;
+                            case Exception ex:
+                                _logger.Error(
+                                    ex,
+                                    $"An unexpected exception occurred during {fname}()."
+                                );
+                                break;
+                        }
+                    });
             }
         }
 
diff --git a/Libplanet/Net/Swarm.cs b/Libplanet/Net/Swarm.cs
index 8f6958a23f..c480f42dfb 100644
--- a/Libplanet/Net/Swarm.cs
+++ b/Libplanet/Net/Swarm.cs
@@ -2098,7 +2098,7 @@ private async Task ProcessFillblock(CancellationToken cancellationToken)
                 if (_demandBlockHash is null ||
                     _demandBlockHash.Value.Item1 <= BlockChain.Tip.Index)
                 {
-                    await Task.Delay(100, cancellationToken);
+                    await Task.Delay(1, cancellationToken);
                     continue;
                 }
 
@@ -2123,7 +2123,6 @@ await SyncPreviousBlocksAsync(
                 catch (TimeoutException)
                 {
                     _logger.Debug($"Timeout occurred during {nameof(ProcessFillblock)}");
-                    await Task.Delay(100, cancellationToken);
                 }
                 catch (Exception e)
                 {
@@ -2141,7 +2140,7 @@ private async Task ProcessFillTxs(CancellationToken cancellationToken)
             {
                 if (_demandTxIds.IsEmpty)
                 {
-                    await Task.Delay(100, cancellationToken);
+                    await Task.Delay(1, cancellationToken);
                     continue;
                 }