diff --git a/src/QueryScheduler.h b/src/QueryScheduler.h
index 72722c82..8a88564b 100644
--- a/src/QueryScheduler.h
+++ b/src/QueryScheduler.h
@@ -7,6 +7,7 @@ struct QueryScheduler : NonCopyable {
     std::function<void(lmdb::txn &txn, const Subscription &sub, uint64_t levId, std::string_view eventPayload)> onEvent;
     std::function<void(lmdb::txn &txn, const Subscription &sub, const std::vector<uint64_t> &levIds)> onEventBatch;
     std::function<void(lmdb::txn &txn, Subscription &sub, uint64_t total)> onComplete;
+    std::function<void(lmdb::txn &txn)> onSliceComplete;
 
     // If false, then levIds returned to above callbacks can be stale (because they were deleted)
     // If false, then onEvent's eventPayload will always be ""
@@ -97,6 +98,8 @@ struct QueryScheduler : NonCopyable {
             levIdBatch.clear();
         }
 
+        if (onSliceComplete) onSliceComplete(txn);
+
         if (complete) {
             auto connId = q->sub.connId;
             removeSub(connId, q->sub.subId);
diff --git a/src/apps/relay/RelayReqMonitor.cpp b/src/apps/relay/RelayReqMonitor.cpp
index 1e6cd4de..78f16fee 100644
--- a/src/apps/relay/RelayReqMonitor.cpp
+++ b/src/apps/relay/RelayReqMonitor.cpp
@@ -38,8 +38,9 @@ void RelayServer::runReqMonitor(ThreadPool<MsgReqMonitor>::Thread &thr) {
                     PackedEventView packed(ev.buf);
                     if (msg->sub.filterGroup.doesMatch(packed)) {
                         if (ReadRestrictor::shouldSendToSubscriber(packed, connAuthedPubkey)) {
-                            sendEvent(connId, msg->sub.subId, getEventJson(txn, decomp, ev.primaryKeyId));
+                            sendEvent(connId, msg->sub.subId, getEventJson(txn, decomp, ev.primaryKeyId), false);
                         }
+                        hubTrigger->send();
                     }
 
                     return true;
diff --git a/src/apps/relay/RelayReqWorker.cpp b/src/apps/relay/RelayReqWorker.cpp
index 56021aea..5d031cc3 100644
--- a/src/apps/relay/RelayReqWorker.cpp
+++ b/src/apps/relay/RelayReqWorker.cpp
@@ -8,6 +8,9 @@ void RelayServer::runReqWorker(ThreadPool<MsgReqWorker>::Thread &thr) {
     QueryScheduler queries;
     flat_hash_map<uint64_t, Bytes32> connIdToAuthedPubkey;
 
+    std::vector<std::string> pendingPayloads;
+    uint64_t pendingConnId = 0;
+
     queries.onEvent = [&](lmdb::txn &txn, const auto &sub, uint64_t levId, std::string_view eventPayload){
         if (sub.countOnly) return;
         auto it = connIdToAuthedPubkey.find(sub.connId);
@@ -15,10 +18,24 @@ void RelayServer::runReqWorker(ThreadPool<MsgReqWorker>::Thread &thr) {
         PackedEventView packed(ev.buf);
         Bytes32 subscriberAuthedPubkey = it == connIdToAuthedPubkey.end() ? Bytes32() : it->second;
         if (!ReadRestrictor::shouldSendToSubscriber(packed, subscriberAuthedPubkey)) {
-            return; 
+            return;
+        }
+        PROM_INC_RELAY_MSG("EVENT");
+        pendingConnId = sub.connId;
+        pendingPayloads.push_back(
+            buildEventReply(sub.subId, decodeEventPayload(txn, decomp, eventPayload, nullptr, nullptr))
+        );
+    };
+
+    queries.onSliceComplete = [&](lmdb::txn &){
+        if (pendingPayloads.empty()) return;
+        if (pendingPayloads.size() == 1) {
+            tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{pendingConnId, std::move(pendingPayloads[0])}});
+        } else {
+            tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::SendBatch{pendingConnId, std::move(pendingPayloads)}});
         }
-        
-        sendEvent(sub.connId, sub.subId, decodeEventPayload(txn, decomp, eventPayload, nullptr, nullptr));
+        pendingPayloads.clear();
+        hubTrigger->send();
     };
 
     queries.onComplete = [&](lmdb::txn &, Subscription &sub, uint64_t total){
diff --git a/src/apps/relay/RelayServer.h b/src/apps/relay/RelayServer.h
index 7767d8c6..547e1669 100644
--- a/src/apps/relay/RelayServer.h
+++ b/src/apps/relay/RelayServer.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstdint>
 #include <iostream>
 #include <memory>
 #include <algorithm>
@@ -36,6 +37,11 @@ struct MsgWebsocket : NonCopyable {
         std::string payload;
     };
 
+    struct SendBatch {
+        uint64_t connId;
+        std::vector<std::string> payloads;
+    };
+
     struct SendEventToBatch {
         RecipientList list;
         std::string evJson;
@@ -44,7 +50,7 @@ struct MsgWebsocket : NonCopyable {
     struct GracefulShutdown {
     };
 
-    using Var = std::variant<Send, SendBinary, SendEventToBatch, GracefulShutdown>;
+    using Var = std::variant<Send, SendBinary, SendBatch, SendEventToBatch, GracefulShutdown>;
     Var msg;
     MsgWebsocket(Var &&msg_) : msg(std::move(msg_)) {}
 };
@@ -213,65 +219,72 @@ struct RelayServer {
 
     // Utils (can be called by any thread)
 
-    void sendToConn(uint64_t connId, std::string &&payload) {
+    void sendToConn(uint64_t connId, std::string &&payload, bool flush = true) {
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{connId, std::move(payload)}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendToConnBinary(uint64_t connId, std::string &&payload) {
+    void sendToConnBinary(uint64_t connId, std::string &&payload, bool flush = true) {
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::SendBinary{connId, std::move(payload)}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendEvent(uint64_t connId, const SubId &subId, std::string_view evJson) {
-        PROM_INC_RELAY_MSG("EVENT");
-        auto subIdSv = subId.sv();
+    void sendToConnBatched(uint64_t connId, std::vector<std::string> &&payloads, bool flush = true) {
+        tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::SendBatch{connId, std::move(payloads)}});
+        if (flush) hubTrigger->send();
+    }
 
+    std::string buildEventReply(const SubId &subId, std::string_view evJson) {
+        auto subIdSv = subId.sv();
         std::string reply;
         reply.reserve(13 + subIdSv.size() + evJson.size());
-
         reply += "[\"EVENT\",\"";
         reply += subIdSv;
         reply += "\",";
         reply += evJson;
         reply += "]";
+        return reply;
+    }
 
-        sendToConn(connId, std::move(reply));
+    void sendEvent(uint64_t connId, const SubId &subId, std::string_view evJson, bool flush = true) {
+        PROM_INC_RELAY_MSG("EVENT");
+        auto reply = buildEventReply(subId, evJson);
+        sendToConn(connId, std::move(reply), flush);
     }
 
-    void sendEventToBatch(RecipientList &&list, std::string &&evJson) {
+    void sendEventToBatch(RecipientList &&list, std::string &&evJson, bool flush = true) {
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::SendEventToBatch{std::move(list), std::move(evJson)}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendNoticeError(uint64_t connId, std::string &&payload) {
+    void sendNoticeError(uint64_t connId, std::string &&payload, bool flush = true) {
         PROM_INC_RELAY_MSG("NOTICE");
         LI << "sending error to [" << connId << "]: " << payload;
         auto reply = tao::json::value::array({ "NOTICE", std::string("ERROR: ") + payload });
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{connId, std::move(tao::json::to_string(reply))}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendClosedError(uint64_t connId, const std::string &subId, std::string &&payload) {
+    void sendClosedError(uint64_t connId, const std::string &subId, std::string &&payload, bool flush = true) {
         PROM_INC_RELAY_MSG("CLOSED");
         LI << "sending closed to [" << connId << "]: " << payload;
         auto reply = tao::json::value::array({ "CLOSED", subId, std::string("ERROR: ") + payload });
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{connId, std::move(tao::json::to_string(reply))}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendOKResponse(uint64_t connId, std::string_view eventIdHex, bool written, std::string_view message) {
+    void sendOKResponse(uint64_t connId, std::string_view eventIdHex, bool written, std::string_view message, bool flush = true) {
         PROM_INC_RELAY_MSG("OK");
         auto reply = tao::json::value::array({ "OK", eventIdHex, written, message });
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{connId, std::move(tao::json::to_string(reply))}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 
-    void sendAuthChallenge(uint64_t connId, std::string_view challenge) {
+    void sendAuthChallenge(uint64_t connId, std::string_view challenge, bool flush = true) {
         PROM_INC_RELAY_MSG("AUTH");
         PrometheusMetrics::getInstance().authChallengesSentTotal.inc();
         auto reply = tao::json::value::array({ "AUTH", challenge });
         tpWebsocket.dispatch(0, MsgWebsocket{MsgWebsocket::Send{connId, std::move(tao::json::to_string(reply))}});
-        hubTrigger->send();
+        if (flush) hubTrigger->send();
     }
 };
diff --git a/src/apps/relay/RelayWebsocket.cpp b/src/apps/relay/RelayWebsocket.cpp
index fbd302a1..a097b7d3 100644
--- a/src/apps/relay/RelayWebsocket.cpp
+++ b/src/apps/relay/RelayWebsocket.cpp
@@ -331,11 +331,7 @@ void RelayServer::runWebsocket(ThreadPool<MsgWebsocket>::Thread &thr) {
     std::function<void()> asyncCb = [&]{
         auto newMsgs = thr.inbox.pop_all_no_wait();
 
-        auto doSend = [&](uint64_t connId, std::string_view payload, uWS::OpCode opCode){
-            auto it = connIdToConnection.find(connId);
-            if (it == connIdToConnection.end()) return;
-            auto &c = *it->second;
-
+        auto doSendToConnection = [&](Connection &c, std::string_view payload, uWS::OpCode opCode) -> bool {
             // Track bytes still inside uWS's outbound path (either queued or
             // partially sent). Increment before send(), decrement in the
             // completion callback. The payload size is smuggled through the
@@ -380,8 +376,15 @@ void RelayServer::runWebsocket(ThreadPool<MsgWebsocket>::Thread &thr) {
                    << renderSize(maxPending) << ", terminating";
                 PrometheusMetrics::getInstance().slowClientTerminations.inc();
                 c.websocket->terminate();
-                return;
+                return false; // signal: connection is dead, stop sending to it
             }
+            return true;
+        };
+
+        auto doSend = [&](uint64_t connId, std::string_view payload, uWS::OpCode opCode){
+            auto it = connIdToConnection.find(connId);
+            if (it == connIdToConnection.end()) return;
+            doSendToConnection(*it->second, payload, opCode);
         };
 
         for (auto &newMsg : newMsgs) {
@@ -389,6 +392,13 @@ void RelayServer::runWebsocket(ThreadPool<MsgWebsocket>::Thread &thr) {
                 doSend(msg->connId, msg->payload, uWS::OpCode::TEXT);
             } else if (auto msg = std::get_if<MsgWebsocket::SendBinary>(&newMsg.msg)) {
                 doSend(msg->connId, msg->payload, uWS::OpCode::BINARY);
+            } else if (auto batch = std::get_if<MsgWebsocket::SendBatch>(&newMsg.msg)) {
+                    auto it = connIdToConnection.find(batch->connId);
+                    if (it == connIdToConnection.end()) continue;
+                    auto &c = *it->second;
+                    for (auto &payload : batch->payloads) {
+                        if (!doSendToConnection(c, payload, uWS::OpCode::TEXT)) break; // terminated, stop
+                }
             } else if (auto msg = std::get_if<MsgWebsocket::SendEventToBatch>(&newMsg.msg)) {
                 tempBuf.reserve(13 + MAX_SUBID_SIZE + msg->evJson.size());
                 tempBuf.resize(10 + MAX_SUBID_SIZE);
diff --git a/test/tests/readRestrictTest.js b/test/tests/readRestrictTest.js
index c1c3cc0e..05a62e3d 100644
--- a/test/tests/readRestrictTest.js
+++ b/test/tests/readRestrictTest.js
@@ -210,8 +210,15 @@ async function testRestrictedFilterReturnsAllIfAuthenticatedAndInvolvementNotReq
 }) {
   // send AUTH message with challenge string
   const authEvent = signEvent(
-    authChallengeString,
-    "wss://relay.test",
+    {
+      kind: 22242,
+      created_at: Math.floor(Date.now() / 1000),
+      tags: [
+        ["relay", "wss://relay.test"],
+        ["challenge", authChallengeString],
+      ],
+      content: "",
+    },
     ids[0].sec,
   );
   client.send(["AUTH", authEvent]);
diff --git a/test/utils/events.js b/test/utils/events.js
index e87f3dfb..265e6b6f 100644
--- a/test/utils/events.js
+++ b/test/utils/events.js
@@ -52,20 +52,7 @@ export function buildEvent({
   return { ...evt, id, sig };
 }
 
-export function signEvent(authChallengeString, relayUrl, sec) {
+export function signEvent(event, sec) {
   const secBytes = hexToBytes(sec);
-  const authEvent = finalizeEvent(
-    {
-      kind: 22242,
-      created_at: Math.floor(Date.now() / 1000),
-      tags: [
-        ["relay", relayUrl],
-        ["challenge", authChallengeString],
-      ],
-      content: "",
-    },
-    secBytes,
-  );
-
-  return authEvent;
+  return finalizeEvent(event, secBytes);
 }