diff --git a/lib/reducers/thread-reducer.js b/lib/reducers/thread-reducer.js
--- a/lib/reducers/thread-reducer.js
+++ b/lib/reducers/thread-reducer.js
@@ -59,19 +59,28 @@
 const { processStoreOperations: processThreadStoreOperations } =
   threadStoreOpsHandlers;
 
-function generateOpsForThreadUpdates(
-  threadInfos: RawThreadInfos,
+function generateOpsAndProcessThreadUpdates(
+  threadStore: ThreadStore,
   newUpdates: $ReadOnlyArray<ClientUpdateInfo>,
-): $ReadOnlyArray<ThreadStoreOperation> {
-  return newUpdates
-    .map(update =>
-      updateSpecs[update.type].generateOpsForThreadUpdates?.(
-        threadInfos,
-        update,
-      ),
-    )
-    .filter(Boolean)
-    .flat();
+): {
+  +threadStoreOperations: $ReadOnlyArray<ThreadStoreOperation>,
+  +updatedThreadStore: ThreadStore,
+} {
+  const operations: Array<ThreadStoreOperation> = [];
+  let store = threadStore;
+  for (const update of newUpdates) {
+    const ops = updateSpecs[update.type].generateOpsForThreadUpdates?.(
+      store.threadInfos,
+      update,
+    );
+    if (!ops || ops.length === 0) {
+      continue;
+    }
+
+    operations.push(...ops);
+    store = processThreadStoreOperations(store, ops);
+  }
+  return { threadStoreOperations: operations, updatedThreadStore: store };
 }
 
 type ReduceThreadInfosResult = {
@@ -261,14 +270,8 @@
         threadStoreOperations: [],
       };
     }
-    const threadStoreOperations = generateOpsForThreadUpdates(
-      state.threadInfos,
-      newUpdates,
-    );
-    const updatedThreadStore = processThreadStoreOperations(
-      state,
-      threadStoreOperations,
-    );
+    const { threadStoreOperations, updatedThreadStore } =
+      generateOpsAndProcessThreadUpdates(state, newUpdates);
     return {
       threadStore: updatedThreadStore,
       newThreadInconsistencies: [],
@@ -286,14 +289,8 @@
         threadStoreOperations: [],
       };
     }
-    const threadStoreOperations = generateOpsForThreadUpdates(
-      state.threadInfos,
-      newUpdates,
-    );
-    const updatedThreadStore = processThreadStoreOperations(
-      state,
-      threadStoreOperations,
-    );
+    const { threadStoreOperations, updatedThreadStore } =
+      generateOpsAndProcessThreadUpdates(state, newUpdates);
     return {
       threadStore: updatedThreadStore,
       newThreadInconsistencies: [],
@@ -544,14 +541,8 @@
         threadStoreOperations: [],
       };
     }
-    const threadStoreOperations = generateOpsForThreadUpdates(
-      state.threadInfos,
-      updateInfos,
-    );
-    const updatedThreadStore = processThreadStoreOperations(
-      state,
-      threadStoreOperations,
-    );
+    const { threadStoreOperations, updatedThreadStore } =
+      generateOpsAndProcessThreadUpdates(state, updateInfos);
     return {
       threadStore: updatedThreadStore,
       newThreadInconsistencies: [],