diff --git a/src/import_pipeline.cc b/src/import_pipeline.cc
index 182b9637..985e5c74 100644
--- a/src/import_pipeline.cc
+++ b/src/import_pipeline.cc
@@ -465,7 +465,7 @@ bool IndexMain_DoCreateIndexUpdate(TimestampManager* timestamp_manager) {
     LOG_S(INFO) << "Applying IndexUpdate" << std::endl << update.ToString();
 #endif
 
-  Index_OnIndexed reply(update, response->perf);
+  Index_OnIndexed reply(std::move(update), response->perf);
   queue->on_indexed.PushBack(std::move(reply), response->is_interactive);
 
   return true;
@@ -502,7 +502,7 @@ bool IndexMergeIndexUpdates() {
 
     did_merge = true;
     Timer time;
-    root->update.Merge(to_join->update);
+    root->update.Merge(std::move(to_join->update));
     // time.ResetAndPrint("Joined querydb updates for files: " +
     // StringJoinMap(root->update.files_def_update,
     //[](const QueryFile::DefUpdate& update) {
diff --git a/src/query.cc b/src/query.cc
index 4e18ddfc..9689cc48 100644
--- a/src/query.cc
+++ b/src/query.cc
@@ -663,7 +663,7 @@ IndexUpdate::IndexUpdate(const IdMap& previous_id_map,
 }
 
 // This function runs on an indexer thread.
-void IndexUpdate::Merge(const IndexUpdate& update) {
+void IndexUpdate::Merge(IndexUpdate&& update) {
 #define INDEX_UPDATE_APPEND(name) AddRange(&name, update.name);
 #define INDEX_UPDATE_MERGE(name) AddMergeableRange(&name, update.name);
 
diff --git a/src/query.h b/src/query.h
index 8f26efab..9c205307 100644
--- a/src/query.h
+++ b/src/query.h
@@ -168,7 +168,7 @@ struct MergeableUpdate {
   std::vector<TValue> to_remove;
 
   MergeableUpdate(TId id, const std::vector<TValue>& to_add)
-      : id(id), to_add(to_add) {}
+    : id(id), to_add(to_add) {}
   MergeableUpdate(TId id,
                   const std::vector<TValue>& to_add,
                   const std::vector<TValue>& to_remove)
@@ -189,6 +189,7 @@ struct WithUsr {
   T value;
 
   WithUsr(Usr usr, const T& value) : usr(usr), value(value) {}
+  WithUsr(Usr usr, T&& value) : usr(usr), value(std::move(value)) {}
 };
 template <typename TVisitor, typename T>
 void Reflect(TVisitor& visitor, WithUsr<T>& value) {
@@ -320,7 +321,7 @@ struct IndexUpdate {
 
   // Merge |update| into this update; this can reduce overhead / index update
   // work can be parallelized.
-  void Merge(const IndexUpdate& update);
+  void Merge(IndexUpdate&& update);
 
   // Dump the update to a string.
   std::string ToString();
diff --git a/src/queue_manager.cc b/src/queue_manager.cc
index d36a796e..5a841708 100644
--- a/src/queue_manager.cc
+++ b/src/queue_manager.cc
@@ -45,9 +45,9 @@ Index_OnIdMapped::Index_OnIdMapped(const std::shared_ptr<ICacheManager>& cache_m
       is_interactive(is_interactive),
       write_to_disk(write_to_disk) {}
 
-Index_OnIndexed::Index_OnIndexed(IndexUpdate& update,
+Index_OnIndexed::Index_OnIndexed(IndexUpdate&& update,
                                  PerformanceImportFile perf)
-    : update(update), perf(perf) {}
+  : update(std::move(update)), perf(perf) {}
 
 QueueManager* QueueManager::instance_ = nullptr;
 
diff --git a/src/queue_manager.h b/src/queue_manager.h
index ddd769d3..bc85194f 100644
--- a/src/queue_manager.h
+++ b/src/queue_manager.h
@@ -76,7 +76,7 @@ struct Index_OnIndexed {
   IndexUpdate update;
   PerformanceImportFile perf;
 
-  Index_OnIndexed(IndexUpdate& update, PerformanceImportFile perf);
+  Index_OnIndexed(IndexUpdate&& update, PerformanceImportFile perf);
 };
 
 struct QueueManager {
diff --git a/src/serializer.cc b/src/serializer.cc
index a3e81bf9..8b6c7dbc 100644
--- a/src/serializer.cc
+++ b/src/serializer.cc
@@ -125,6 +125,19 @@ void Reflect(Writer& visitor, std::string_view& data) {
     visitor.String(&data[0], (rapidjson::SizeType)data.size());
 }
 
+void Reflect(Reader& visitor, std::unique_ptr<char[]>& value) {
+  if (!visitor.IsString())
+    throw std::invalid_argument("std::string");
+  std::string t = visitor.GetString();
+  value = std::unique_ptr<char[]>(new char[t.size() + 1]);
+  strcpy(value.get(), t.c_str());
+}
+void Reflect(Writer& visitor, std::unique_ptr<char[]>& value) {
+  if (!value)
+    visitor.String("");
+  else
+    visitor.String(value.get());
+}
 
 // TODO: Move this to indexer.cc
 void Reflect(Reader& visitor, IndexInclude& value) {
@@ -155,6 +168,7 @@ void ReflectHoverAndComments(Reader& visitor, Def& def) {
 
 template <typename Def>
 void ReflectHoverAndComments(Writer& visitor, Def& def) {
+  // Don't emit empty hover and comments in JSON test mode.
   if (!gTestOutputMode || def.hover.size())
     ReflectMember(visitor, "hover", def.hover);
   if (!gTestOutputMode || def.comments.size())
diff --git a/src/serializer.h b/src/serializer.h
index b53aeeb5..714b6c10 100644
--- a/src/serializer.h
+++ b/src/serializer.h
@@ -160,6 +160,9 @@ void Reflect(Writer& visitor, std::string& value);
 void Reflect(Reader& visitor, std::string_view& view);
 void Reflect(Writer& visitor, std::string_view& view);
 
+void Reflect(Reader& visitor, std::unique_ptr<char[]>& value);
+void Reflect(Writer& visitor, std::unique_ptr<char[]>& value);
+
 // std::monostate is used to represent JSON null
 void Reflect(Reader& visitor, std::monostate&);
 void Reflect(Writer& visitor, std::monostate&);
@@ -303,7 +306,7 @@ void Reflect(Reader& visitor, std::vector<T>& values) {
   visitor.IterArray([&](Reader& entry) {
     T entry_value;
     Reflect(entry, entry_value);
-    values.push_back(entry_value);
+    values.push_back(std::move(entry_value));
   });
 }
 template <typename T>
diff --git a/src/utils.h b/src/utils.h
index 0de383cc..a7fca9f0 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -135,6 +135,12 @@ void AddRange(std::vector<T>* dest, const std::vector<T>& to_add) {
   dest->insert(dest->end(), to_add.begin(), to_add.end());
 }
 
+template <typename T>
+void AddRange(std::vector<T>* dest, std::vector<T>&& to_add) {
+  for (T& x : to_add)
+    dest->push_back(std::move(x));
+}
+
 template <typename T>
 void PushRange(std::queue<T>* dest, const std::vector<T>& to_add) {
   for (const T& e : to_add)
diff --git a/third_party/loguru b/third_party/loguru
index bead3888..37e48808 160000
--- a/third_party/loguru
+++ b/third_party/loguru
@@ -1 +1 @@
-Subproject commit bead38889d44d9fdb5c52916d1f26c4d6af09e66
+Subproject commit 37e48808d720194199bc273be4184402a0bc394a