diff --git a/assignment-client/src/audio/AudioMixerSlave.cpp b/assignment-client/src/audio/AudioMixerSlave.cpp
index 7a6ab9c3e2..681d822e11 100644
--- a/assignment-client/src/audio/AudioMixerSlave.cpp
+++ b/assignment-client/src/audio/AudioMixerSlave.cpp
@@ -504,7 +504,7 @@ void AudioMixerSlave::addStream(AudioMixerClientData::MixableStream& mixableStre
     float distance = glm::max(glm::length(relativePosition), EPSILON);
     float azimuth = isEcho ? 0.0f : computeAzimuth(listeningNodeStream, listeningNodeStream, relativePosition);
 
-    float gain = 1.0f;
+    float gain = masterListenerGain;
     if (!isSoloing) {
         gain = computeGain(masterListenerGain, listeningNodeStream, *streamToAdd, relativePosition, distance, isEcho);
     }
diff --git a/assignment-client/src/avatars/AvatarMixer.cpp b/assignment-client/src/avatars/AvatarMixer.cpp
index 62b58f3d73..6b90a8fbbd 100644
--- a/assignment-client/src/avatars/AvatarMixer.cpp
+++ b/assignment-client/src/avatars/AvatarMixer.cpp
@@ -56,6 +56,7 @@ AvatarMixer::AvatarMixer(ReceivedMessage& message) :
     packetReceiver.registerListener(PacketType::RequestsDomainListData, this, "handleRequestsDomainListDataPacket");
     packetReceiver.registerListener(PacketType::AvatarIdentityRequest, this, "handleAvatarIdentityRequestPacket");
     packetReceiver.registerListener(PacketType::SetAvatarTraits, this, "queueIncomingPacket");
+    packetReceiver.registerListener(PacketType::BulkAvatarTraitsAck, this, "queueIncomingPacket");
 
     packetReceiver.registerListenerForTypes({
         PacketType::ReplicatedAvatarIdentity,
diff --git a/assignment-client/src/avatars/AvatarMixerClientData.cpp b/assignment-client/src/avatars/AvatarMixerClientData.cpp
index 7313634cff..7f1b40142e 100644
--- a/assignment-client/src/avatars/AvatarMixerClientData.cpp
+++ b/assignment-client/src/avatars/AvatarMixerClientData.cpp
@@ -19,9 +19,8 @@
 
 #include "AvatarMixerSlave.h"
 
-AvatarMixerClientData::AvatarMixerClientData(const QUuid& nodeID, Node::LocalID nodeLocalID) :
-    NodeData(nodeID, nodeLocalID)
-{
+AvatarMixerClientData::AvatarMixerClientData(const QUuid& nodeID, Node::LocalID nodeLocalID) : 
+    NodeData(nodeID, nodeLocalID) {
     // in case somebody calls getSessionUUID on the AvatarData instance, make sure it has the right ID
     _avatar->setID(nodeID);
 }
@@ -68,6 +67,9 @@ int AvatarMixerClientData::processPackets(const SlaveSharedData& slaveSharedData
             case PacketType::SetAvatarTraits:
                 processSetTraitsMessage(*packet, slaveSharedData, *node);
                 break;
+            case PacketType::BulkAvatarTraitsAck:
+                processBulkAvatarTraitsAckMessage(*packet);
+                break;
             default:
                 Q_UNREACHABLE();
         }
@@ -79,12 +81,11 @@ int AvatarMixerClientData::processPackets(const SlaveSharedData& slaveSharedData
 }
 
 int AvatarMixerClientData::parseData(ReceivedMessage& message) {
-
     // pull the sequence number from the data first
     uint16_t sequenceNumber;
 
     message.readPrimitive(&sequenceNumber);
-    
+
     if (sequenceNumber < _lastReceivedSequenceNumber && _lastReceivedSequenceNumber != UINT16_MAX) {
         incrementNumOutOfOrderSends();
     }
@@ -95,7 +96,8 @@ int AvatarMixerClientData::parseData(ReceivedMessage& message) {
 }
 
 void AvatarMixerClientData::processSetTraitsMessage(ReceivedMessage& message,
-                                                    const SlaveSharedData& slaveSharedData, Node& sendingNode) {
+                                                    const SlaveSharedData& slaveSharedData,
+                                                    Node& sendingNode) {
     // pull the trait version from the message
     AvatarTraits::TraitVersion packetTraitVersion;
     message.readPrimitive(&packetTraitVersion);
@@ -134,7 +136,7 @@ void AvatarMixerClientData::processSetTraitsMessage(ReceivedMessage& message,
             AvatarTraits::TraitInstanceID instanceID = QUuid::fromRfc4122(message.readWithoutCopy(NUM_BYTES_RFC4122_UUID));
 
             if (message.getBytesLeftToRead() == 0) {
-                qWarning () << "Received an instanced trait with no size from" << message.getSenderSockAddr();
+                qWarning() << "Received an instanced trait with no size from" << message.getSenderSockAddr();
                 break;
             }
 
@@ -142,7 +144,8 @@ void AvatarMixerClientData::processSetTraitsMessage(ReceivedMessage& message,
             message.readPrimitive(&traitSize);
 
             if (traitSize < -1 || traitSize > message.getBytesLeftToRead()) {
-                qWarning() << "Refusing to process instanced trait of size" << traitSize << "from" << message.getSenderSockAddr();
+                qWarning() << "Refusing to process instanced trait of size" << traitSize << "from"
+                           << message.getSenderSockAddr();
                 break;
             }
 
@@ -169,7 +172,8 @@ void AvatarMixerClientData::processSetTraitsMessage(ReceivedMessage& message,
                     message.seek(message.getPosition() + traitSize);
                 }
             } else {
-                qWarning() << "Refusing to process traits packet with instanced trait of unprocessable type from" << message.getSenderSockAddr();
+                qWarning() << "Refusing to process traits packet with instanced trait of unprocessable type from"
+                           << message.getSenderSockAddr();
                 break;
             }
         }
@@ -180,7 +184,61 @@ void AvatarMixerClientData::processSetTraitsMessage(ReceivedMessage& message,
     }
 }
 
-void AvatarMixerClientData::checkSkeletonURLAgainstWhitelist(const SlaveSharedData &slaveSharedData, Node& sendingNode,
+void AvatarMixerClientData::processBulkAvatarTraitsAckMessage(ReceivedMessage& message) {
+    // Avatar Traits flow control marks each outgoing avatar traits packet with a
+    // sequence number. The mixer caches the traits sent in the traits packet.
+    // Until an ack with the sequence number comes back, all updates to _traits
+    // in that packet_ are ignored.  Updates to traits not in that packet will
+    // be sent.
+
+    // Look up the avatar/trait data associated with this ack and update the 'last ack' list
+    // with it.
+    AvatarTraits::TraitMessageSequence seq;
+    message.readPrimitive(&seq);
+    auto sentAvatarTraitVersions = _perNodePendingTraitVersions.find(seq);
+    if (sentAvatarTraitVersions != _perNodePendingTraitVersions.end()) {
+        for (auto& perNodeTraitVersions : sentAvatarTraitVersions->second) {
+            auto& nodeId = perNodeTraitVersions.first;
+            auto& traitVersions = perNodeTraitVersions.second;
+            // For each trait that was sent in the traits packet,
+            // update the 'acked' trait version.  Traits not
+            // sent in the traits packet keep their version.
+
+            // process simple traits
+            auto simpleReceivedIt = traitVersions.simpleCBegin();
+            while (simpleReceivedIt != traitVersions.simpleCEnd()) {
+                auto traitType = static_cast<AvatarTraits::TraitType>(std::distance(traitVersions.simpleCBegin(), simpleReceivedIt));
+                _perNodeAckedTraitVersions[nodeId][traitType] = *simpleReceivedIt;
+                simpleReceivedIt++;
+            }
+
+            // process instanced traits
+            auto instancedSentIt = traitVersions.instancedCBegin();
+            while (instancedSentIt != traitVersions.instancedCEnd()) {
+                auto traitType = instancedSentIt->traitType;
+
+                for (auto& sentInstance : instancedSentIt->instances) {
+                    auto instanceID = sentInstance.id;
+                    const auto sentVersion = sentInstance.value;
+                    _perNodeAckedTraitVersions[nodeId].instanceInsert(traitType, instanceID, sentVersion);
+                }
+                instancedSentIt++;
+            }
+        }
+        _perNodePendingTraitVersions.erase(sentAvatarTraitVersions);
+    } else {
+        // This can happen either the BulkAvatarTraits was sent with no simple traits,
+        // or if the avatar mixer restarts while there are pending
+        // BulkAvatarTraits messages in-flight.
+        if (seq > getTraitsMessageSequence()) {
+            qWarning() << "Received BulkAvatarTraitsAck with future seq (potential avatar mixer restart) " << seq << " from "
+                       << message.getSenderSockAddr();
+        }
+    }
+}
+
+void AvatarMixerClientData::checkSkeletonURLAgainstWhitelist(const SlaveSharedData& slaveSharedData,
+                                                             Node& sendingNode,
                                                              AvatarTraits::TraitVersion traitVersion) {
     const auto& whitelist = slaveSharedData.skeletonURLWhitelist;
 
@@ -282,14 +340,14 @@ void AvatarMixerClientData::removeFromRadiusIgnoringSet(const QUuid& other) {
 
 void AvatarMixerClientData::resetSentTraitData(Node::LocalID nodeLocalID) {
     _lastSentTraitsTimestamps[nodeLocalID] = TraitsCheckTimestamp();
-    _sentTraitVersions[nodeLocalID].reset();
+    _perNodeSentTraitVersions[nodeLocalID].reset();
 }
 
 void AvatarMixerClientData::readViewFrustumPacket(const QByteArray& message) {
     _currentViewFrustums.clear();
 
     auto sourceBuffer = reinterpret_cast<const unsigned char*>(message.constData());
-    
+
     uint8_t numFrustums = 0;
     memcpy(&numFrustums, sourceBuffer, sizeof(numFrustums));
     sourceBuffer += sizeof(numFrustums);
@@ -339,5 +397,5 @@ void AvatarMixerClientData::cleanupKilledNode(const QUuid&, Node::LocalID nodeLo
     removeLastBroadcastSequenceNumber(nodeLocalID);
     removeLastBroadcastTime(nodeLocalID);
     _lastSentTraitsTimestamps.erase(nodeLocalID);
-    _sentTraitVersions.erase(nodeLocalID);
+    _perNodeSentTraitVersions.erase(nodeLocalID);
 }
diff --git a/assignment-client/src/avatars/AvatarMixerClientData.h b/assignment-client/src/avatars/AvatarMixerClientData.h
index 18144b1e01..843f19cf22 100644
--- a/assignment-client/src/avatars/AvatarMixerClientData.h
+++ b/assignment-client/src/avatars/AvatarMixerClientData.h
@@ -43,6 +43,7 @@ public:
     AvatarMixerClientData(const QUuid& nodeID, Node::LocalID nodeLocalID);
     virtual ~AvatarMixerClientData() {}
     using HRCTime = p_high_resolution_clock::time_point;
+    using PerNodeTraitVersions = std::unordered_map<Node::LocalID, AvatarTraits::TraitVersions>;
 
     int parseData(ReceivedMessage& message) override;
     AvatarData& getAvatar() { return *_avatar; }
@@ -130,6 +131,7 @@ public:
     int processPackets(const SlaveSharedData& slaveSharedData); // returns number of packets processed
 
     void processSetTraitsMessage(ReceivedMessage& message, const SlaveSharedData& slaveSharedData, Node& sendingNode);
+    void processBulkAvatarTraitsAckMessage(ReceivedMessage& message);
     void checkSkeletonURLAgainstWhitelist(const SlaveSharedData& slaveSharedData, Node& sendingNode,
                                           AvatarTraits::TraitVersion traitVersion);
 
@@ -144,7 +146,14 @@ public:
     void setLastOtherAvatarTraitsSendPoint(Node::LocalID otherAvatar, TraitsCheckTimestamp sendPoint)
         { _lastSentTraitsTimestamps[otherAvatar] = sendPoint; }
 
-    AvatarTraits::TraitVersions& getLastSentTraitVersions(Node::LocalID otherAvatar) { return _sentTraitVersions[otherAvatar]; }
+    AvatarTraits::TraitMessageSequence getTraitsMessageSequence() const { return _currentTraitsMessageSequence; }
+    AvatarTraits::TraitMessageSequence nextTraitsMessageSequence() { return ++_currentTraitsMessageSequence; }
+    AvatarTraits::TraitVersions& getPendingTraitVersions(AvatarTraits::TraitMessageSequence seq, Node::LocalID otherId) {
+        return _perNodePendingTraitVersions[seq][otherId];
+    }
+
+    AvatarTraits::TraitVersions& getLastSentTraitVersions(Node::LocalID otherAvatar) { return _perNodeSentTraitVersions[otherAvatar]; }
+    AvatarTraits::TraitVersions& getLastAckedTraitVersions(Node::LocalID otherAvatar) { return _perNodeAckedTraitVersions[otherAvatar]; }
 
     void resetSentTraitData(Node::LocalID nodeID);
 
@@ -190,8 +199,27 @@ private:
     AvatarTraits::TraitVersions _lastReceivedTraitVersions;
     TraitsCheckTimestamp _lastReceivedTraitsChange;
 
+    AvatarTraits::TraitMessageSequence _currentTraitsMessageSequence{ 0 };
+
+    // Cache of trait versions sent in a given packet (indexed by sequence number)
+    // When an ack is received, the sequence number in the ack is used to look up
+    // the sent trait versions and they are copied to _perNodeAckedTraitVersions.
+    // We remember the data in _perNodePendingTraitVersions instead of requiring
+    // the client to return all of the versions for each trait it received in a given packet,
+    // reducing the size of the ack packet.
+    std::unordered_map<AvatarTraits::TraitMessageSequence, PerNodeTraitVersions> _perNodePendingTraitVersions;
+
+    // Versions of traits that have been acked, which will be compared to incoming
+    // trait updates.  Incoming updates going to a given node will be ignored if 
+    // the ack for the previous packet (containing those versions) has not been
+    // received.
+    PerNodeTraitVersions _perNodeAckedTraitVersions;
+
     std::unordered_map<Node::LocalID, TraitsCheckTimestamp> _lastSentTraitsTimestamps;
-    std::unordered_map<Node::LocalID, AvatarTraits::TraitVersions> _sentTraitVersions;
+
+    // cache of traits sent to a node which are compared to incoming traits to 
+    // prevent sending traits that have already been sent.
+    PerNodeTraitVersions _perNodeSentTraitVersions;
 
     std::atomic_bool _isIgnoreRadiusEnabled { false };
 };
diff --git a/assignment-client/src/avatars/AvatarMixerSlave.cpp b/assignment-client/src/avatars/AvatarMixerSlave.cpp
index 0460407f01..5e84df0d7f 100644
--- a/assignment-client/src/avatars/AvatarMixerSlave.cpp
+++ b/assignment-client/src/avatars/AvatarMixerSlave.cpp
@@ -81,10 +81,31 @@ int AvatarMixerSlave::sendIdentityPacket(NLPacketList& packetList, const AvatarM
     }
 }
 
+qint64 AvatarMixerSlave::addTraitsNodeHeader(AvatarMixerClientData* listeningNodeData,
+                                             const AvatarMixerClientData* sendingNodeData,
+                                             NLPacketList& traitsPacketList,
+                                             qint64 bytesWritten) {
+    if (bytesWritten == 0) {
+        if (traitsPacketList.getNumPackets() == 0) {
+            // This is the beginning of the traits packet, write out the sequence number.
+            bytesWritten += traitsPacketList.writePrimitive(listeningNodeData->nextTraitsMessageSequence());
+        }
+        // This is the beginning of the traits for a node, write out the node id
+        bytesWritten += traitsPacketList.write(sendingNodeData->getNodeID().toRfc4122());
+    }
+    return bytesWritten;
+}
+
 qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* listeningNodeData,
                                                       const AvatarMixerClientData* sendingNodeData,
                                                       NLPacketList& traitsPacketList) {
 
+    // Avatar Traits flow control marks each outgoing avatar traits packet with a
+    // sequence number. The mixer caches the traits sent in the traits packet.
+    // Until an ack with the sequence number comes back, all updates to _traits
+    // in that packet_ are ignored.  Updates to traits not in that packet will
+    // be sent.
+
     auto otherNodeLocalID = sendingNodeData->getNodeLocalID();
 
     // Perform a simple check with two server clock time points
@@ -97,13 +118,11 @@ qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* lis
     if (timeOfLastTraitsChange > timeOfLastTraitsSent) {
         // there is definitely new traits data to send
 
-        // add the avatar ID to mark the beginning of traits for this avatar
-        bytesWritten += traitsPacketList.write(sendingNodeData->getNodeID().toRfc4122());
-
         auto sendingAvatar = sendingNodeData->getAvatarSharedPointer();
 
         // compare trait versions so we can see what exactly needs to go out
         auto& lastSentVersions = listeningNodeData->getLastSentTraitVersions(otherNodeLocalID);
+        auto& lastAckedVersions = listeningNodeData->getLastAckedTraitVersions(otherNodeLocalID);
         const auto& lastReceivedVersions = sendingNodeData->getLastReceivedTraitVersions();
 
         auto simpleReceivedIt = lastReceivedVersions.simpleCBegin();
@@ -112,13 +131,19 @@ qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* lis
                                                                                 simpleReceivedIt));
             auto lastReceivedVersion = *simpleReceivedIt;
             auto& lastSentVersionRef = lastSentVersions[traitType];
+            auto& lastAckedVersionRef = lastAckedVersions[traitType];
 
-            if (lastReceivedVersions[traitType] > lastSentVersionRef) {
+            // hold sending more traits until we've been acked that the last one we sent was received
+            if (lastSentVersionRef == lastAckedVersionRef && lastReceivedVersions[traitType] > lastSentVersionRef) {
+                bytesWritten += addTraitsNodeHeader(listeningNodeData, sendingNodeData, traitsPacketList, bytesWritten);
                 // there is an update to this trait, add it to the traits packet
                 bytesWritten += sendingAvatar->packTrait(traitType, traitsPacketList, lastReceivedVersion);
-
                 // update the last sent version
                 lastSentVersionRef = lastReceivedVersion;
+                // Remember which versions we sent in this particular packet
+                // so we can verify when it's acked.
+                auto& pendingTraitVersions = listeningNodeData->getPendingTraitVersions(listeningNodeData->getTraitsMessageSequence(), otherNodeLocalID);
+                pendingTraitVersions[traitType] = lastReceivedVersion;
             }
 
             ++simpleReceivedIt;
@@ -131,6 +156,7 @@ qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* lis
 
             // get or create the sent trait versions for this trait type
             auto& sentIDValuePairs = lastSentVersions.getInstanceIDValuePairs(traitType);
+            auto& ackIDValuePairs = lastAckedVersions.getInstanceIDValuePairs(traitType);
 
             // enumerate each received instance
             for (auto& receivedInstance : instancedReceivedIt->instances) {
@@ -148,8 +174,18 @@ qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* lis
                                                    {
                                                        return sentInstance.id == instanceID;
                                                    });
-
+                // look for existing acked version for this instance
+                auto ackedInstanceIt = std::find_if(ackIDValuePairs.begin(), ackIDValuePairs.end(),
+                                                    [instanceID](auto& ackInstance) { return ackInstance.id == instanceID; });
+                
+                // if we have a sent version, then we must have an acked instance of the same trait with the same
+                // version to go on, otherwise we drop the received trait
+                if (sentInstanceIt != sentIDValuePairs.end() &&
+                    (ackedInstanceIt == ackIDValuePairs.end() || sentInstanceIt->value != ackedInstanceIt->value)) {
+                    continue;
+                }
                 if (!isDeleted && (sentInstanceIt == sentIDValuePairs.end() || receivedVersion > sentInstanceIt->value)) {
+                    bytesWritten += addTraitsNodeHeader(listeningNodeData, sendingNodeData, traitsPacketList, bytesWritten);
 
                     // this instance version exists and has never been sent or is newer so we need to send it
                     bytesWritten += sendingAvatar->packTraitInstance(traitType, instanceID, traitsPacketList, receivedVersion);
@@ -159,22 +195,35 @@ qint64 AvatarMixerSlave::addChangedTraitsToBulkPacket(AvatarMixerClientData* lis
                     } else {
                         sentIDValuePairs.emplace_back(instanceID, receivedVersion);
                     }
+
+                    auto& pendingTraitVersions =
+                        listeningNodeData->getPendingTraitVersions(listeningNodeData->getTraitsMessageSequence(),
+                                                                   otherNodeLocalID);
+                    pendingTraitVersions.instanceInsert(traitType, instanceID, receivedVersion);
+
                 } else if (isDeleted && sentInstanceIt != sentIDValuePairs.end() && absoluteReceivedVersion > sentInstanceIt->value) {
+                    bytesWritten += addTraitsNodeHeader(listeningNodeData, sendingNodeData, traitsPacketList, bytesWritten);
 
                     // this instance version was deleted and we haven't sent the delete to this client yet
                     bytesWritten += AvatarTraits::packInstancedTraitDelete(traitType, instanceID, traitsPacketList, absoluteReceivedVersion);
 
                     // update the last sent version for this trait instance to the absolute value of the deleted version
                     sentInstanceIt->value = absoluteReceivedVersion;
+
+                    auto& pendingTraitVersions =
+                        listeningNodeData->getPendingTraitVersions(listeningNodeData->getTraitsMessageSequence(),
+                                                                   otherNodeLocalID);
+                    pendingTraitVersions.instanceInsert(traitType, instanceID, absoluteReceivedVersion);
+
                 }
             }
 
             ++instancedReceivedIt;
         }
-
-        // write a null trait type to mark the end of trait data for this avatar
-        bytesWritten += traitsPacketList.writePrimitive(AvatarTraits::NullTrait);
-
+        if (bytesWritten) {
+            // write a null trait type to mark the end of trait data for this avatar
+            bytesWritten += traitsPacketList.writePrimitive(AvatarTraits::NullTrait);
+        }
         // since we send all traits for this other avatar, update the time of last traits sent
         // to match the time of last traits change
         listeningNodeData->setLastOtherAvatarTraitsSendPoint(otherNodeLocalID, timeOfLastTraitsChange);
@@ -420,6 +469,7 @@ void AvatarMixerSlave::broadcastAvatarDataToAgent(const SharedNodePointer& node)
 
     int remainingAvatars = (int)sortedAvatars.size();
     auto traitsPacketList = NLPacketList::create(PacketType::BulkAvatarTraits, QByteArray(), true, true);
+
     auto avatarPacket = NLPacket::create(PacketType::BulkAvatarData);
     const int avatarPacketCapacity = avatarPacket->getPayloadCapacity();
     int avatarSpaceAvailable = avatarPacketCapacity;
diff --git a/assignment-client/src/avatars/AvatarMixerSlave.h b/assignment-client/src/avatars/AvatarMixerSlave.h
index 5c38cda590..91bb02fd55 100644
--- a/assignment-client/src/avatars/AvatarMixerSlave.h
+++ b/assignment-client/src/avatars/AvatarMixerSlave.h
@@ -114,6 +114,11 @@ private:
     int sendIdentityPacket(NLPacketList& packet, const AvatarMixerClientData* nodeData, const Node& destinationNode);
     int sendReplicatedIdentityPacket(const Node& agentNode, const AvatarMixerClientData* nodeData, const Node& destinationNode);
 
+    qint64 addTraitsNodeHeader(AvatarMixerClientData* listeningNodeData,
+                               const AvatarMixerClientData* sendingNodeData,
+                               NLPacketList& traitsPacketList,
+                               qint64 bytesWritten);
+
     qint64 addChangedTraitsToBulkPacket(AvatarMixerClientData* listeningNodeData,
                                         const AvatarMixerClientData* sendingNodeData,
                                         NLPacketList& traitsPacketList);
diff --git a/interface/src/Application.cpp b/interface/src/Application.cpp
index d306c77cce..134c375b56 100644
--- a/interface/src/Application.cpp
+++ b/interface/src/Application.cpp
@@ -2060,7 +2060,7 @@ Application::Application(int& argc, char** argv, QElapsedTimer& startupTimer, bo
         properties["avatar_ping"] = avatarMixerNode ? avatarMixerNode->getPingMs() : -1;
         properties["asset_ping"] = assetServerNode ? assetServerNode->getPingMs() : -1;
         properties["messages_ping"] = messagesMixerNode ? messagesMixerNode->getPingMs() : -1;
-        properties["atp_in_kbps"] = messagesMixerNode ? assetServerNode->getInboundKbps() : 0.0f;
+        properties["atp_in_kbps"] = assetServerNode ? assetServerNode->getInboundKbps() : 0.0f;
 
         auto loadingRequests = ResourceCache::getLoadingRequests();
 
diff --git a/interface/src/AvatarBookmarks.cpp b/interface/src/AvatarBookmarks.cpp
index ee639f602d..1d003f19c1 100644
--- a/interface/src/AvatarBookmarks.cpp
+++ b/interface/src/AvatarBookmarks.cpp
@@ -60,7 +60,6 @@ void addAvatarEntities(const QVariantList& avatarEntities) {
         entityProperties.setParentID(myNodeID);
         entityProperties.setEntityHostType(entity::HostType::AVATAR);
         entityProperties.setOwningAvatarID(myNodeID);
-        entityProperties.setSimulationOwner(myNodeID, AVATAR_ENTITY_SIMULATION_PRIORITY);
         entityProperties.markAllChanged();
 
         EntityItemID id = EntityItemID(QUuid::createUuid());
diff --git a/interface/src/ui/overlays/Base3DOverlay.cpp b/interface/src/ui/overlays/Base3DOverlay.cpp
index eab7a96a4b..eb43e8cf45 100644
--- a/interface/src/ui/overlays/Base3DOverlay.cpp
+++ b/interface/src/ui/overlays/Base3DOverlay.cpp
@@ -27,6 +27,9 @@ Base3DOverlay::Base3DOverlay() :
     _drawInFront(false),
     _drawHUDLayer(false)
 {
+    // HACK: queryAACube stuff not actually relevant for 3DOverlays, and by setting _queryAACubeSet true here
+    // we can avoid incorrect evaluation for sending updates for entities with 3DOverlays children.
+    _queryAACubeSet = true;
 }
 
 Base3DOverlay::Base3DOverlay(const Base3DOverlay* base3DOverlay) :
@@ -41,6 +44,9 @@ Base3DOverlay::Base3DOverlay(const Base3DOverlay* base3DOverlay) :
     _isVisibleInSecondaryCamera(base3DOverlay->_isVisibleInSecondaryCamera)
 {
     setTransform(base3DOverlay->getTransform());
+    // HACK: queryAACube stuff not actually relevant for 3DOverlays, and by setting _queryAACubeSet true here
+    // we can avoid incorrect evaluation for sending updates for entities with 3DOverlays children.
+    _queryAACubeSet = true;
 }
 
 QVariantMap convertOverlayLocationFromScriptSemantics(const QVariantMap& properties, bool scalesWithParent) {
@@ -209,6 +215,7 @@ void Base3DOverlay::setProperties(const QVariantMap& originalProperties) {
             transaction.updateItem(itemID);
             scene->enqueueTransaction(transaction);
         }
+        _queryAACubeSet = true; // HACK: just in case some SpatiallyNestable code accidentally set it false
     }
 }
 
diff --git a/interface/src/ui/overlays/Base3DOverlay.h b/interface/src/ui/overlays/Base3DOverlay.h
index 6cc5182b56..daf15e676f 100644
--- a/interface/src/ui/overlays/Base3DOverlay.h
+++ b/interface/src/ui/overlays/Base3DOverlay.h
@@ -25,6 +25,7 @@ public:
     Base3DOverlay(const Base3DOverlay* base3DOverlay);
 
     void setVisible(bool visible) override;
+    bool queryAACubeNeedsUpdate() const override { return false; } // HACK: queryAACube not relevant for Overlays
 
     virtual OverlayID getOverlayID() const override { return OverlayID(getID().toString()); }
     void setOverlayID(OverlayID overlayID) override { setID(overlayID); }
diff --git a/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp b/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
index 0676454b29..dbf5899386 100644
--- a/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
+++ b/libraries/avatars-renderer/src/avatars-renderer/Avatar.cpp
@@ -394,10 +394,6 @@ void Avatar::updateAvatarEntities() {
             properties.setEntityHostType(entity::HostType::AVATAR);
             properties.setOwningAvatarID(getID());
 
-            // there's no entity-server to tell us we're the simulation owner, so always set the
-            // simulationOwner to the owningAvatarID and a high priority.
-            properties.setSimulationOwner(getID(), AVATAR_ENTITY_SIMULATION_PRIORITY);
-
             if (properties.getParentID() == AVATAR_SELF_ID) {
                 properties.setParentID(getID());
             }
diff --git a/libraries/avatars/src/AvatarHashMap.cpp b/libraries/avatars/src/AvatarHashMap.cpp
index 41ca950b3b..6a67ef6638 100644
--- a/libraries/avatars/src/AvatarHashMap.cpp
+++ b/libraries/avatars/src/AvatarHashMap.cpp
@@ -328,6 +328,19 @@ void AvatarHashMap::processAvatarIdentityPacket(QSharedPointer<ReceivedMessage>
 }
 
 void AvatarHashMap::processBulkAvatarTraits(QSharedPointer<ReceivedMessage> message, SharedNodePointer sendingNode) {
+    AvatarTraits::TraitMessageSequence seq;
+
+    message->readPrimitive(&seq);
+
+    auto traitsAckPacket = NLPacket::create(PacketType::BulkAvatarTraitsAck, sizeof(AvatarTraits::TraitMessageSequence), true);
+    traitsAckPacket->writePrimitive(seq);
+    auto nodeList = DependencyManager::get<LimitedNodeList>();
+    SharedNodePointer avatarMixer = nodeList->soloNodeOfType(NodeType::AvatarMixer);
+    if (!avatarMixer.isNull()) {
+        // we have a mixer to send to, acknowledge that we received these
+        // traits.
+        nodeList->sendPacket(std::move(traitsAckPacket), *avatarMixer);
+    }
 
     while (message->getBytesLeftToRead()) {
         // read the avatar ID to figure out which avatar this is for
diff --git a/libraries/avatars/src/AvatarTraits.h b/libraries/avatars/src/AvatarTraits.h
index 0f4ad0b90f..4516572e42 100644
--- a/libraries/avatars/src/AvatarTraits.h
+++ b/libraries/avatars/src/AvatarTraits.h
@@ -42,6 +42,10 @@ namespace AvatarTraits {
     const TraitWireSize DELETED_TRAIT_SIZE = -1;
     const TraitWireSize MAXIMUM_TRAIT_SIZE = INT16_MAX;
 
+    using TraitMessageSequence = int64_t;
+    const TraitMessageSequence FIRST_TRAIT_SEQUENCE = 0;
+    const TraitMessageSequence MAX_TRAIT_SEQUENCE = INT64_MAX;
+
     inline qint64 packInstancedTraitDelete(TraitType traitType, TraitInstanceID instanceID, ExtendedIODevice& destination,
                                          TraitVersion traitVersion = NULL_TRAIT_VERSION) {
         qint64 bytesWritten = 0;
diff --git a/libraries/entities/src/EntityItemProperties.h b/libraries/entities/src/EntityItemProperties.h
index 12ae940952..17ec83be78 100644
--- a/libraries/entities/src/EntityItemProperties.h
+++ b/libraries/entities/src/EntityItemProperties.h
@@ -157,7 +157,7 @@ public:
     DEFINE_PROPERTY(PROP_CREATED, Created, created, quint64, UNKNOWN_CREATED_TIME);
     DEFINE_PROPERTY_REF(PROP_LAST_EDITED_BY, LastEditedBy, lastEditedBy, QUuid, ENTITY_ITEM_DEFAULT_LAST_EDITED_BY);
     DEFINE_PROPERTY_REF_ENUM(PROP_ENTITY_HOST_TYPE, EntityHostType, entityHostType, entity::HostType, entity::HostType::DOMAIN);
-    DEFINE_PROPERTY_REF(PROP_OWNING_AVATAR_ID, OwningAvatarID, owningAvatarID, QUuid, UNKNOWN_ENTITY_ID);
+    DEFINE_PROPERTY_REF_WITH_SETTER(PROP_OWNING_AVATAR_ID, OwningAvatarID, owningAvatarID, QUuid, UNKNOWN_ENTITY_ID);
     DEFINE_PROPERTY_REF(PROP_PARENT_ID, ParentID, parentID, QUuid, UNKNOWN_ENTITY_ID);
     DEFINE_PROPERTY_REF(PROP_PARENT_JOINT_INDEX, ParentJointIndex, parentJointIndex, quint16, -1);
     DEFINE_PROPERTY_REF(PROP_QUERY_AA_CUBE, QueryAACube, queryAACube, AACube, AACube());
@@ -499,6 +499,16 @@ void EntityPropertyInfoFromScriptValue(const QScriptValue& object, EntityPropert
 inline void EntityItemProperties::setPosition(const glm::vec3& value)
                     { _position = glm::clamp(value, (float)-HALF_TREE_SCALE, (float)HALF_TREE_SCALE); _positionChanged = true; }
 
+inline void EntityItemProperties::setOwningAvatarID(const QUuid& id) {
+    _owningAvatarID = id;
+    if (!_owningAvatarID.isNull()) {
+        // for AvatarEntities there's no entity-server to tell us we're the simulation owner,
+        // so always set the simulationOwner to the owningAvatarID and a high priority.
+        setSimulationOwner(_owningAvatarID, AVATAR_ENTITY_SIMULATION_PRIORITY);
+    }
+    _owningAvatarIDChanged = true;
+}
+
 QDebug& operator<<(QDebug& dbg, const EntityPropertyFlags& f);
 
 inline QDebug operator<<(QDebug debug, const EntityItemProperties& properties) {
diff --git a/libraries/entities/src/SimulationOwner.h b/libraries/entities/src/SimulationOwner.h
index 353255728c..bd444d28dd 100644
--- a/libraries/entities/src/SimulationOwner.h
+++ b/libraries/entities/src/SimulationOwner.h
@@ -96,7 +96,7 @@ const uint8_t RECRUIT_SIMULATION_PRIORITY = VOLUNTEER_SIMULATION_PRIORITY + 1;
 // When poking objects with scripts an observer will bid at SCRIPT_EDIT priority.
 const uint8_t SCRIPT_GRAB_SIMULATION_PRIORITY = 128;
 const uint8_t SCRIPT_POKE_SIMULATION_PRIORITY = SCRIPT_GRAB_SIMULATION_PRIORITY - 1;
-const uint8_t AVATAR_ENTITY_SIMULATION_PRIORITY = SCRIPT_GRAB_SIMULATION_PRIORITY + 1;
+const uint8_t AVATAR_ENTITY_SIMULATION_PRIORITY = 255;
 
 // PERSONAL priority (needs a better name) is the level at which a simulation observer owns its own avatar
 // which really just means: things that collide with it will be bid at a priority level one lower
diff --git a/libraries/networking/src/udt/PacketHeaders.cpp b/libraries/networking/src/udt/PacketHeaders.cpp
index 114a0bc930..aba3822883 100644
--- a/libraries/networking/src/udt/PacketHeaders.cpp
+++ b/libraries/networking/src/udt/PacketHeaders.cpp
@@ -97,6 +97,9 @@ PacketVersion versionForPacketType(PacketType packetType) {
             return 22;
         case PacketType::EntityQueryInitialResultsComplete:
             return static_cast<PacketVersion>(EntityVersion::ParticleSpin);
+        case PacketType::BulkAvatarTraitsAck:
+        case PacketType::BulkAvatarTraits:
+            return static_cast<PacketVersion>(AvatarMixerPacketVersion::AvatarTraitsAck);
         default:
             return 22;
     }
diff --git a/libraries/networking/src/udt/PacketHeaders.h b/libraries/networking/src/udt/PacketHeaders.h
index 88b52ec4fb..6f019f39b6 100644
--- a/libraries/networking/src/udt/PacketHeaders.h
+++ b/libraries/networking/src/udt/PacketHeaders.h
@@ -133,7 +133,7 @@ public:
         EntityQueryInitialResultsComplete,
         BulkAvatarTraits,
         AudioSoloRequest,
-
+        BulkAvatarTraitsAck,
         NUM_PACKET_TYPE
     };
 
@@ -310,7 +310,8 @@ enum class AvatarMixerPacketVersion : PacketVersion {
     FarGrabJointsRedux,
     JointTransScaled,
     GrabTraits,
-    CollisionFlag
+    CollisionFlag,
+    AvatarTraitsAck
 };
 
 enum class DomainConnectRequestVersion : PacketVersion {
diff --git a/libraries/networking/src/udt/SendQueue.cpp b/libraries/networking/src/udt/SendQueue.cpp
index b507f0921d..15841b5c21 100644
--- a/libraries/networking/src/udt/SendQueue.cpp
+++ b/libraries/networking/src/udt/SendQueue.cpp
@@ -61,6 +61,9 @@ private:
     Mutex2& _mutex2;
 };
 
+const microseconds SendQueue::MAXIMUM_ESTIMATED_TIMEOUT = seconds(5);
+const microseconds SendQueue::MINIMUM_ESTIMATED_TIMEOUT = milliseconds(10);
+
 std::unique_ptr<SendQueue> SendQueue::create(Socket* socket, HifiSockAddr destination, SequenceNumber currentSequenceNumber,
                                              MessageNumber currentMessageNumber, bool hasReceivedHandshakeACK) {
     Q_ASSERT_X(socket, "SendQueue::create", "Must be called with a valid Socket*");
@@ -507,12 +510,8 @@ bool SendQueue::isInactive(bool attemptedToSendPacket) {
 
                 auto estimatedTimeout = std::chrono::microseconds(_estimatedTimeout);
 
-                // cap our maximum estimated timeout to the already unreasonable 5 seconds
-                const auto MAXIMUM_ESTIMATED_TIMEOUT = std::chrono::seconds(5);
-
-                if (estimatedTimeout > MAXIMUM_ESTIMATED_TIMEOUT) {
-                    estimatedTimeout = MAXIMUM_ESTIMATED_TIMEOUT;
-                }
+                // Clamp timeout beween 10 ms and 5 s
+                estimatedTimeout = std::min(MAXIMUM_ESTIMATED_TIMEOUT, std::max(MINIMUM_ESTIMATED_TIMEOUT, estimatedTimeout));
 
                 // use our condition_variable_any to wait
                 auto cvStatus = _emptyCondition.wait_for(locker, estimatedTimeout);
diff --git a/libraries/networking/src/udt/SendQueue.h b/libraries/networking/src/udt/SendQueue.h
index 148d813fc1..c1a2b59075 100644
--- a/libraries/networking/src/udt/SendQueue.h
+++ b/libraries/networking/src/udt/SendQueue.h
@@ -140,6 +140,9 @@ private:
     std::condition_variable_any _emptyCondition;
 
     std::chrono::high_resolution_clock::time_point _lastPacketSentAt;
+
+    static const std::chrono::microseconds MAXIMUM_ESTIMATED_TIMEOUT;
+    static const std::chrono::microseconds MINIMUM_ESTIMATED_TIMEOUT;
 };
     
 }
diff --git a/libraries/physics/src/EntityMotionState.cpp b/libraries/physics/src/EntityMotionState.cpp
index dd906fe5c1..9814e358c3 100644
--- a/libraries/physics/src/EntityMotionState.cpp
+++ b/libraries/physics/src/EntityMotionState.cpp
@@ -306,6 +306,8 @@ const btCollisionShape* EntityMotionState::computeNewShape() {
     return getShapeManager()->getShape(shapeInfo);
 }
 
+const uint8_t MAX_NUM_INACTIVE_UPDATES = 20;
+
 bool EntityMotionState::remoteSimulationOutOfSync(uint32_t simulationStep) {
     // NOTE: this method is only ever called when the entity simulation is locally owned
     DETAILED_PROFILE_RANGE(simulation_physics, "CheckOutOfSync");
@@ -315,15 +317,10 @@ bool EntityMotionState::remoteSimulationOutOfSync(uint32_t simulationStep) {
     // TODO: need to be able to detect when logic dictates we *decrease* priority
     // WIP: print info whenever _bidPriority mismatches what is known to the entity
 
-    if (_entity->dynamicDataNeedsTransmit()) {
-        return true;
-    }
-
     int numSteps = simulationStep - _lastStep;
     float dt = (float)(numSteps) * PHYSICS_ENGINE_FIXED_SUBSTEP;
 
     if (_numInactiveUpdates > 0) {
-        const uint8_t MAX_NUM_INACTIVE_UPDATES = 20;
         if (_numInactiveUpdates > MAX_NUM_INACTIVE_UPDATES) {
             // clear local ownership (stop sending updates) and let the server clear itself
             _entity->clearSimulationOwnership();
@@ -451,8 +448,13 @@ void EntityMotionState::updateSendVelocities() {
         if (!_body->isKinematicObject()) {
             clearObjectVelocities();
         }
-        // we pretend we sent the inactive update for this object
-        _numInactiveUpdates = 1;
+        if (_entity->getEntityHostType() == entity::HostType::AVATAR) {
+            // AvatarEntities only ever need to send one update (their updates are sent over a lossless protocol)
+            // so we set the count to the max to prevent resends
+            _numInactiveUpdates = MAX_NUM_INACTIVE_UPDATES;
+        } else {
+            ++_numInactiveUpdates;
+        }
     } else {
         glm::vec3 gravity = _entity->getGravity();