diff --git a/PubSub.cpp b/PubSub.cpp
index c2ddd9dd1354..1092b2a3ca77 100644
--- a/PubSub.cpp
+++ b/PubSub.cpp
@@ -40,39 +40,30 @@ std::shared_ptr<const Publisher::Item> Publisher::Subscriber::getNext() {
   return nullptr;
 }
 
-std::vector<std::shared_ptr<const Publisher::Item>>
-Publisher::Subscriber::getPending() {
-  std::vector<std::shared_ptr<const Publisher::Item>> items;
-
-  auto rlock = publisher_->state_.rlock();
-  for (auto& item : rlock->items) {
-    if (item->serial > serial_) {
-      serial_ = item->serial;
-      items.push_back(item);
+void Publisher::Subscriber::getPending(
+    std::vector<std::shared_ptr<const Item>>& pending) {
+  {
+    auto rlock = publisher_->state_.rlock();
+    for (auto& item : rlock->items) {
+      auto serial = item->serial;
+      if (serial > serial_) {
+        pending.emplace_back(item);
+        serial_ = serial;
+      }
     }
   }
-
-  return items;
-}
-
-template <typename Vec>
-void moveVec(Vec& dest, Vec&& src) {
-  std::move(src.begin(), src.end(), std::back_inserter(dest));
 }
 
-std::vector<std::shared_ptr<const Publisher::Item>> getPending(
+void getPending(
+    std::vector<std::shared_ptr<const Publisher::Item>>& items,
     const std::shared_ptr<Publisher::Subscriber>& sub1,
     const std::shared_ptr<Publisher::Subscriber>& sub2) {
-  std::vector<std::shared_ptr<const Publisher::Item>> items;
-
   if (sub1) {
-    moveVec(items, sub1->getPending());
+    sub1->getPending(items);
   }
   if (sub2) {
-    moveVec(items, sub2->getPending());
+    sub2->getPending(items);
   }
-
-  return items;
 }
 
 std::shared_ptr<Publisher::Subscriber> Publisher::subscribe(Notifier notify) {
diff --git a/PubSub.h b/PubSub.h
index bfe57fa216f3..59a099b7d5a9 100644
--- a/PubSub.h
+++ b/PubSub.h
@@ -47,7 +47,7 @@ class Publisher : public std::enable_shared_from_this<Publisher> {
     // Returns all as yet unseen published items for this subscriber.
     // Equivalent to calling getNext in a loop and sticking the results
     // into a vector.
-    std::vector<std::shared_ptr<const Item>> getPending();
+    void getPending(std::vector<std::shared_ptr<const Item>>& pending);
 
     inline uint64_t getSerial() const {
       return serial_;
@@ -91,7 +91,8 @@ class Publisher : public std::enable_shared_from_this<Publisher> {
 
 // Equivalent to calling getPending on up to two Subscriber and
 // joining the resultant vectors together.
-std::vector<std::shared_ptr<const Publisher::Item>> getPending(
+void getPending(
+    std::vector<std::shared_ptr<const Publisher::Item>>& pending,
     const std::shared_ptr<Publisher::Subscriber>& sub1,
     const std::shared_ptr<Publisher::Subscriber>& sub2);
 }
diff --git a/cmds/trigger.cpp b/cmds/trigger.cpp
index cda9cfed2823..c8356622e9a2 100644
--- a/cmds/trigger.cpp
+++ b/cmds/trigger.cpp
@@ -31,6 +31,7 @@ bool watchman_trigger_command::waitNoIntr() {
 }
 
 void watchman_trigger_command::run(const std::shared_ptr<w_root_t>& root) {
+  std::vector<std::shared_ptr<const watchman::Publisher::Item>> pending;
   w_set_thread_name(
       "trigger %s %s", triggername.c_str(), root->root_path.c_str());
 
@@ -45,10 +46,17 @@ void watchman_trigger_command::run(const std::shared_ptr<w_root_t>& root) {
       break;
     }
     while (ping_->testAndClear()) {
-      while (auto item = subscriber_->getNext()) {
-        if (!item->payload.get_default("settled")) {
-          continue;
+      pending.clear();
+      subscriber_->getPending(pending);
+      bool seenSettle = false;
+      for (auto& item : pending) {
+        if (item->payload.get_default("settled")) {
+          seenSettle = true;
+          break;
         }
+      }
+
+      if (seenSettle) {
         if (!maybeSpawn(root)) {
           continue;
         }
diff --git a/listener.cpp b/listener.cpp
index d4213807066b..174304cdcad5 100644
--- a/listener.cpp
+++ b/listener.cpp
@@ -125,6 +125,9 @@ static void client_thread(std::shared_ptr<watchman_client> client) {
   struct watchman_event_poll pfd[2];
   json_error_t jerr;
   bool send_ok = true;
+  // Keep a persistent vector around so that we can avoid allocating
+  // and releasing heap memory when we collect items from the publisher
+  std::vector<std::shared_ptr<const watchman::Publisher::Item>> pending;
 
   client->stm->setNonBlock(true);
   w_set_thread_name(
@@ -178,8 +181,9 @@ static void client_thread(std::shared_ptr<watchman_client> client) {
     if (pfd[1].ready) {
       while (client->ping->testAndClear()) {
         // Enqueue refs to pending log payloads
-        auto items = watchman::getPending(client->debugSub, client->errorSub);
-        for (auto& item : items) {
+        pending.clear();
+        getPending(pending, client->debugSub, client->errorSub);
+        for (auto& item : pending) {
           client->enqueueResponse(json_ref(item->payload), false);
         }
 
@@ -196,12 +200,10 @@ static void client_thread(std::shared_ptr<watchman_client> client) {
             watchman::log(
                 watchman::DBG, "consider fan out sub ", sub->name, "\n");
 
-            while (true) {
-              auto item = subStream->getNext();
-              if (!item) {
-                break;
-              }
-
+            pending.clear();
+            subStream->getPending(pending);
+            bool seenSettle = false;
+            for (auto& item : pending) {
               auto dumped = json_dumps(item->payload, 0);
               watchman::log(
                   watchman::DBG,
@@ -250,10 +252,14 @@ static void client_thread(std::shared_ptr<watchman_client> client) {
               }
 
               if (item->payload.get_default("settled")) {
-                sub->processSubscription();
+                seenSettle = true;
                 continue;
               }
             }
+
+            if (seenSettle) {
+              sub->processSubscription();
+            }
           }
 
           for (auto& name : subsToDelete) {
diff --git a/log.cpp b/log.cpp
index 6a4b4d016070..58e885d11e76 100644
--- a/log.cpp
+++ b/log.cpp
@@ -157,7 +157,8 @@ void Log::setStdErrLoggingLevel(enum LogLevel level) {
 }
 
 void Log::doLogToStdErr() {
-  auto items = getPending(errorSub_, debugSub_);
+  std::vector<std::shared_ptr<const watchman::Publisher::Item>> items;
+  getPending(items, errorSub_, debugSub_);
 
   bool fatal = false;
   static w_string kFatal("fatal");