diff --git a/lib/reducers/user-reducer.js b/lib/reducers/user-reducer.js
--- a/lib/reducers/user-reducer.js
+++ b/lib/reducers/user-reducer.js
@@ -272,6 +272,9 @@
     const filteredUserIDs = action.payload.userIDs.filter(
       id => !state.userInfos[id],
     );
+    if (filteredUserIDs.length === 0) {
+      return [state, [], []];
+    }
     const newUserInfosArray = filteredUserIDs.map(id => ({
       id,
       username: null,
@@ -286,15 +289,16 @@
       state.userInfos,
       userStoreOps,
     );
-
-    return [
-      {
-        ...state,
-        userInfos: processedUserInfos,
-      },
-      [],
-      userStoreOps,
-    ];
+    if (!_isEqual(state.userInfos)(processedUserInfos)) {
+      return [
+        {
+          ...state,
+          userInfos: processedUserInfos,
+        },
+        [],
+        userStoreOps,
+      ];
+    }
   } else if (
     action.type === joinThreadActionTypes.success ||
     action.type === newThreadActionTypes.success