diff --git a/lib/reducers/message-reducer.js b/lib/reducers/message-reducer.js
--- a/lib/reducers/message-reducer.js
+++ b/lib/reducers/message-reducer.js
@@ -10,7 +10,6 @@
 import _mapValues from 'lodash/fp/mapValues.js';
 import _omit from 'lodash/fp/omit.js';
 import _omitBy from 'lodash/fp/omitBy.js';
-import _pick from 'lodash/fp/pick.js';
 import _pickBy from 'lodash/fp/pickBy.js';
 import _uniq from 'lodash/fp/uniq.js';
 
@@ -674,23 +673,18 @@
   } = reassignMessagesToRealizedThreads(messageStore, threadInfos);
   messageStoreOperations.push(...reassignMessagesOps);
   const watchedIDs = [...threadWatcher.getWatchedIDs(), ...reassignedThreadIDs];
-  const watchedThreadInfos = _pickBy((threadInfo: RawThreadInfo) =>
-    isThreadWatched(threadInfo.id, threadInfo, watchedIDs),
-  )(threadInfos);
 
-  const filteredThreads = _pick(Object.keys(watchedThreadInfos))(
-    reassignedMessageStore.threads,
-  );
-
-  const messageIDsToRemove = [];
+  const filteredThreads = {};
   const threadsToRemoveMessagesFrom = [];
+  const messageIDsToRemove = [];
   for (const threadID in reassignedMessageStore.threads) {
-    if (watchedThreadInfos[threadID]) {
-      continue;
-    }
-    threadsToRemoveMessagesFrom.push(threadID);
-    for (const id of reassignedMessageStore.threads[threadID].messageIDs) {
-      messageIDsToRemove.push(id);
+    const threadMessageInfo = reassignedMessageStore.threads[threadID];
+    const threadInfo = threadInfos[threadID];
+    if (isThreadWatched(threadID, threadInfo, watchedIDs)) {
+      filteredThreads[threadID] = threadMessageInfo;
+    } else {
+      threadsToRemoveMessagesFrom.push(threadID);
+      messageIDsToRemove.push(...threadMessageInfo.messageIDs);
     }
   }