diff --git a/packages/react-native/Libraries/Components/View/__tests__/View-benchmark-itest.js b/packages/react-native/Libraries/Components/View/__tests__/View-benchmark-itest.js
index 5d19b6c52a1e..10930caf2f98 100644
--- a/packages/react-native/Libraries/Components/View/__tests__/View-benchmark-itest.js
+++ b/packages/react-native/Libraries/Components/View/__tests__/View-benchmark-itest.js
@@ -17,6 +17,31 @@ import {View} from 'react-native';
 let root;
 let testViews: React.MixedElement;
 
+function createDeepViewHierarchy(depth: number, breadth: number): React.Node {
+  if (depth === 0) {
+    return (
+      <View
+        collapsable={false}
+        style={{width: 10, height: 10}}
+        nativeID="leaf"
+      />
+    );
+  }
+  const children = [];
+  for (let i = 0; i < breadth; i++) {
+    children.push(
+      <View
+        key={i}
+        collapsable={false}
+        nativeID={`d${depth.toString()}-${i.toString()}`}
+        style={{width: depth + 1, height: depth + 1}}>
+        {createDeepViewHierarchy(depth - 1, breadth)}
+      </View>,
+    );
+  }
+  return <View collapsable={false}>{children}</View>;
+}
+
 function createViewsWithLargeAmountOfPropsAndStyles(count: number): React.Node {
   let views: React.Node = null;
   for (let i = 0; i < count; i++) {
@@ -124,4 +149,28 @@ Fantom.unstable_benchmark
         root.destroy();
       },
     }),
+  )
+  .test.each(
+    [
+      [5, 4],
+      [7, 3],
+      [10, 2],
+    ],
+    ([depth, breadth]) =>
+      `render deep view hierarchy (depth=${depth.toString()}, breadth=${breadth.toString()})`,
+    () => {
+      Fantom.runTask(() => root.render(testViews));
+    },
+    ([depth, breadth]) => ({
+      beforeAll: () => {
+        // $FlowExpectedError[incompatible-type]
+        testViews = createDeepViewHierarchy(depth, breadth);
+      },
+      beforeEach: () => {
+        root = Fantom.createRoot();
+      },
+      afterEach: () => {
+        root.destroy();
+      },
+    }),
   );
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt
index 3e0e99e6af11..65d5f0c5328c 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlags.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<477777b9a795b57f3bb3eaeb030738a9>>
+ * @generated SignedSource<<4e5ae706df013f43dd19f98cf905a138>>
  */
 
 /**
@@ -498,6 +498,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun useSharedAnimatedBackend(): Boolean = accessor.useSharedAnimatedBackend()
 
+  /**
+   * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+   */
+  @JvmStatic
+  public fun useUnorderedMapInDifferentiator(): Boolean = accessor.useUnorderedMapInDifferentiator()
+
   /**
    * Use Trait::hidden on Android
    */
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt
index bbd27b4d6433..ade8d499f7aa 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxAccessor.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c7b6ea7f1672df7bb3396375378784c5>>
+ * @generated SignedSource<<6d7e2160c022ae4630f8d3a4b263621f>>
  */
 
 /**
@@ -98,6 +98,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
   private var useNestedScrollViewAndroidCache: Boolean? = null
   private var useSharedAnimatedBackendCache: Boolean? = null
+  private var useUnorderedMapInDifferentiatorCache: Boolean? = null
   private var useTraitHiddenOnAndroidCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
@@ -807,6 +808,15 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
     return cached
   }
 
+  override fun useUnorderedMapInDifferentiator(): Boolean {
+    var cached = useUnorderedMapInDifferentiatorCache
+    if (cached == null) {
+      cached = ReactNativeFeatureFlagsCxxInterop.useUnorderedMapInDifferentiator()
+      useUnorderedMapInDifferentiatorCache = cached
+    }
+    return cached
+  }
+
   override fun useTraitHiddenOnAndroid(): Boolean {
     var cached = useTraitHiddenOnAndroidCache
     if (cached == null) {
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt
index 5aa0113e15e4..ec78931b8323 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsCxxInterop.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<ec036cff49622b8c2b52d2f9eaa59e6c>>
+ * @generated SignedSource<<be5acfe89b6f852a5910eec7dae4e888>>
  */
 
 /**
@@ -184,6 +184,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun useSharedAnimatedBackend(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun useUnorderedMapInDifferentiator(): Boolean
+
   @DoNotStrip @JvmStatic public external fun useTraitHiddenOnAndroid(): Boolean
 
   @DoNotStrip @JvmStatic public external fun useTurboModuleInterop(): Boolean
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt
index 0950fb163232..e50a533e7e4e 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsDefaults.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<523e3c35d4bd1fc85f2a3bb26b8aad3f>>
+ * @generated SignedSource<<fa4bdf78bba37dbc514735cc3618efee>>
  */
 
 /**
@@ -179,6 +179,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun useSharedAnimatedBackend(): Boolean = false
 
+  override fun useUnorderedMapInDifferentiator(): Boolean = false
+
   override fun useTraitHiddenOnAndroid(): Boolean = false
 
   override fun useTurboModuleInterop(): Boolean = false
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt
index 656dbba20689..39c65d4c2fb0 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsLocalAccessor.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<cfd6a4514be320519a57566182b73f69>>
+ * @generated SignedSource<<c53d8309f47b1fd7845953a5b64c955f>>
  */
 
 /**
@@ -102,6 +102,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var useNativeViewConfigsInBridgelessModeCache: Boolean? = null
   private var useNestedScrollViewAndroidCache: Boolean? = null
   private var useSharedAnimatedBackendCache: Boolean? = null
+  private var useUnorderedMapInDifferentiatorCache: Boolean? = null
   private var useTraitHiddenOnAndroidCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
@@ -889,6 +890,16 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
     return cached
   }
 
+  override fun useUnorderedMapInDifferentiator(): Boolean {
+    var cached = useUnorderedMapInDifferentiatorCache
+    if (cached == null) {
+      cached = currentProvider.useUnorderedMapInDifferentiator()
+      accessedFeatureFlags.add("useUnorderedMapInDifferentiator")
+      useUnorderedMapInDifferentiatorCache = cached
+    }
+    return cached
+  }
+
   override fun useTraitHiddenOnAndroid(): Boolean {
     var cached = useTraitHiddenOnAndroidCache
     if (cached == null) {
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt
index bb2f3ac62adf..da32f0a57545 100644
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/internal/featureflags/ReactNativeFeatureFlagsProvider.kt
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<bbaa4d1498f606886341d34a62acb508>>
+ * @generated SignedSource<<07b19c2cdde81032b3181a658e528b18>>
  */
 
 /**
@@ -179,6 +179,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun useSharedAnimatedBackend(): Boolean
 
+  @DoNotStrip public fun useUnorderedMapInDifferentiator(): Boolean
+
   @DoNotStrip public fun useTraitHiddenOnAndroid(): Boolean
 
   @DoNotStrip public fun useTurboModuleInterop(): Boolean
diff --git a/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp b/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp
index 15c606bb8072..53e070d28e41 100644
--- a/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp
+++ b/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.cpp
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<45063df01d7ce8726b4a7d901f1b3341>>
+ * @generated SignedSource<<fda512b00459c5aaffae8738e74afe15>>
  */
 
 /**
@@ -507,6 +507,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useUnorderedMapInDifferentiator");
+    return method(javaProvider_);
+  }
+
   bool useTraitHiddenOnAndroid() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useTraitHiddenOnAndroid");
@@ -937,6 +943,11 @@ bool JReactNativeFeatureFlagsCxxInterop::useSharedAnimatedBackend(
   return ReactNativeFeatureFlags::useSharedAnimatedBackend();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::useUnorderedMapInDifferentiator(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::useUnorderedMapInDifferentiator();
+}
+
 bool JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::useTraitHiddenOnAndroid();
@@ -1232,6 +1243,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "useSharedAnimatedBackend",
         JReactNativeFeatureFlagsCxxInterop::useSharedAnimatedBackend),
+      makeNativeMethod(
+        "useUnorderedMapInDifferentiator",
+        JReactNativeFeatureFlagsCxxInterop::useUnorderedMapInDifferentiator),
       makeNativeMethod(
         "useTraitHiddenOnAndroid",
         JReactNativeFeatureFlagsCxxInterop::useTraitHiddenOnAndroid),
diff --git a/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h b/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h
index f5cd383bdeeb..6e21b3fb93a4 100644
--- a/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h
+++ b/packages/react-native/ReactAndroid/src/main/jni/react/featureflags/JReactNativeFeatureFlagsCxxInterop.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<5ac93ed057017f8d1a388b8029614f18>>
+ * @generated SignedSource<<519ec7b20ed2b4feaf10d1448c68c255>>
  */
 
 /**
@@ -264,6 +264,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool useSharedAnimatedBackend(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool useUnorderedMapInDifferentiator(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static bool useTraitHiddenOnAndroid(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp
index 37f971aad1bb..25468778268c 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.cpp
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<9d81f74c5926706ee353813e594575e8>>
+ * @generated SignedSource<<168ae9f867afd3e316d3ba4925ffa07e>>
  */
 
 /**
@@ -338,6 +338,10 @@ bool ReactNativeFeatureFlags::useSharedAnimatedBackend() {
   return getAccessor().useSharedAnimatedBackend();
 }
 
+bool ReactNativeFeatureFlags::useUnorderedMapInDifferentiator() {
+  return getAccessor().useUnorderedMapInDifferentiator();
+}
+
 bool ReactNativeFeatureFlags::useTraitHiddenOnAndroid() {
   return getAccessor().useTraitHiddenOnAndroid();
 }
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h
index 8a1ca2766b22..d3d62c0bd488 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<84e2800073ffab2313a4e27897c0c246>>
+ * @generated SignedSource<<88bd716e389c2929f48a4e400170f7fa>>
  */
 
 /**
@@ -429,6 +429,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool useSharedAnimatedBackend();
 
+  /**
+   * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+   */
+  RN_EXPORT static bool useUnorderedMapInDifferentiator();
+
   /**
    * Use Trait::hidden on Android
    */
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp
index aafd52dd5889..f0514fabe5a4 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<8f9f3ced66040f8275073e5084765356>>
+ * @generated SignedSource<<5c22b9b03b250ee9b535182780651784>>
  */
 
 /**
@@ -1433,6 +1433,24 @@ bool ReactNativeFeatureFlagsAccessor::useSharedAnimatedBackend() {
   return flagValue.value();
 }
 
+bool ReactNativeFeatureFlagsAccessor::useUnorderedMapInDifferentiator() {
+  auto flagValue = useUnorderedMapInDifferentiator_.load();
+
+  if (!flagValue.has_value()) {
+    // This block is not exclusive but it is not necessary.
+    // If multiple threads try to initialize the feature flag, we would only
+    // be accessing the provider multiple times but the end state of this
+    // instance and the returned flag value would be the same.
+
+    markFlagAsAccessed(78, "useUnorderedMapInDifferentiator");
+
+    flagValue = currentProvider_->useUnorderedMapInDifferentiator();
+    useUnorderedMapInDifferentiator_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 bool ReactNativeFeatureFlagsAccessor::useTraitHiddenOnAndroid() {
   auto flagValue = useTraitHiddenOnAndroid_.load();
 
@@ -1442,7 +1460,7 @@ bool ReactNativeFeatureFlagsAccessor::useTraitHiddenOnAndroid() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(78, "useTraitHiddenOnAndroid");
+    markFlagAsAccessed(79, "useTraitHiddenOnAndroid");
 
     flagValue = currentProvider_->useTraitHiddenOnAndroid();
     useTraitHiddenOnAndroid_ = flagValue;
@@ -1460,7 +1478,7 @@ bool ReactNativeFeatureFlagsAccessor::useTurboModuleInterop() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(79, "useTurboModuleInterop");
+    markFlagAsAccessed(80, "useTurboModuleInterop");
 
     flagValue = currentProvider_->useTurboModuleInterop();
     useTurboModuleInterop_ = flagValue;
@@ -1478,7 +1496,7 @@ bool ReactNativeFeatureFlagsAccessor::useTurboModules() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(80, "useTurboModules");
+    markFlagAsAccessed(81, "useTurboModules");
 
     flagValue = currentProvider_->useTurboModules();
     useTurboModules_ = flagValue;
@@ -1496,7 +1514,7 @@ double ReactNativeFeatureFlagsAccessor::viewCullingOutsetRatio() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(81, "viewCullingOutsetRatio");
+    markFlagAsAccessed(82, "viewCullingOutsetRatio");
 
     flagValue = currentProvider_->viewCullingOutsetRatio();
     viewCullingOutsetRatio_ = flagValue;
@@ -1514,7 +1532,7 @@ bool ReactNativeFeatureFlagsAccessor::viewTransitionEnabled() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(82, "viewTransitionEnabled");
+    markFlagAsAccessed(83, "viewTransitionEnabled");
 
     flagValue = currentProvider_->viewTransitionEnabled();
     viewTransitionEnabled_ = flagValue;
@@ -1532,7 +1550,7 @@ double ReactNativeFeatureFlagsAccessor::virtualViewPrerenderRatio() {
     // be accessing the provider multiple times but the end state of this
     // instance and the returned flag value would be the same.
 
-    markFlagAsAccessed(83, "virtualViewPrerenderRatio");
+    markFlagAsAccessed(84, "virtualViewPrerenderRatio");
 
     flagValue = currentProvider_->virtualViewPrerenderRatio();
     virtualViewPrerenderRatio_ = flagValue;
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h
index 28f655e04c0e..c83ec768b872 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<6ba661fd9ce6aeff6cc9269848230618>>
+ * @generated SignedSource<<0c58dd7fbd5561ec62dd5c25d1351336>>
  */
 
 /**
@@ -110,6 +110,7 @@ class ReactNativeFeatureFlagsAccessor {
   bool useNativeViewConfigsInBridgelessMode();
   bool useNestedScrollViewAndroid();
   bool useSharedAnimatedBackend();
+  bool useUnorderedMapInDifferentiator();
   bool useTraitHiddenOnAndroid();
   bool useTurboModuleInterop();
   bool useTurboModules();
@@ -127,7 +128,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::unique_ptr<ReactNativeFeatureFlagsProvider> currentProvider_;
   bool wasOverridden_;
 
-  std::array<std::atomic<const char*>, 84> accessedFeatureFlags_;
+  std::array<std::atomic<const char*>, 85> accessedFeatureFlags_;
 
   std::atomic<std::optional<bool>> commonTestFlag_;
   std::atomic<std::optional<bool>> cdpInteractionMetricsEnabled_;
@@ -207,6 +208,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::atomic<std::optional<bool>> useNativeViewConfigsInBridgelessMode_;
   std::atomic<std::optional<bool>> useNestedScrollViewAndroid_;
   std::atomic<std::optional<bool>> useSharedAnimatedBackend_;
+  std::atomic<std::optional<bool>> useUnorderedMapInDifferentiator_;
   std::atomic<std::optional<bool>> useTraitHiddenOnAndroid_;
   std::atomic<std::optional<bool>> useTurboModuleInterop_;
   std::atomic<std::optional<bool>> useTurboModules_;
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h
index e17c94e91f53..a4348f0d5955 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<861e4a47ad9b2aa4ac054059082724a0>>
+ * @generated SignedSource<<874dda2a17484941b243bc90e08d1192>>
  */
 
 /**
@@ -339,6 +339,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
     return false;
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    return false;
+  }
+
   bool useTraitHiddenOnAndroid() override {
     return false;
   }
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h
index 56c0e084c0f9..74515fae6178 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<774ffd15e1fd9a79bb7b3f6c4719ba23>>
+ * @generated SignedSource<<85e793611d955290f8263ecb23092f46>>
  */
 
 /**
@@ -747,6 +747,15 @@ class ReactNativeFeatureFlagsDynamicProvider : public ReactNativeFeatureFlagsDef
     return ReactNativeFeatureFlagsDefaults::useSharedAnimatedBackend();
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    auto value = values_["useUnorderedMapInDifferentiator"];
+    if (!value.isNull()) {
+      return value.getBool();
+    }
+
+    return ReactNativeFeatureFlagsDefaults::useUnorderedMapInDifferentiator();
+  }
+
   bool useTraitHiddenOnAndroid() override {
     auto value = values_["useTraitHiddenOnAndroid"];
     if (!value.isNull()) {
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h
index cadf99532f4c..c4f392855720 100644
--- a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h
+++ b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsProvider.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<c075c9058ed6fa1761209cdabea376f5>>
+ * @generated SignedSource<<0526ff6c17eb9a0b36e580e4d643aa23>>
  */
 
 /**
@@ -103,6 +103,7 @@ class ReactNativeFeatureFlagsProvider {
   virtual bool useNativeViewConfigsInBridgelessMode() = 0;
   virtual bool useNestedScrollViewAndroid() = 0;
   virtual bool useSharedAnimatedBackend() = 0;
+  virtual bool useUnorderedMapInDifferentiator() = 0;
   virtual bool useTraitHiddenOnAndroid() = 0;
   virtual bool useTurboModuleInterop() = 0;
   virtual bool useTurboModules() = 0;
diff --git a/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp b/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp
index 2d845642de15..3a28d498fcd8 100644
--- a/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp
+++ b/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.cpp
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<0356babbe4e65071e6cc56a06e68b944>>
+ * @generated SignedSource<<4f0b6e01a4df551f79a46e2fc6bd269d>>
  */
 
 /**
@@ -434,6 +434,11 @@ bool NativeReactNativeFeatureFlags::useSharedAnimatedBackend(
   return ReactNativeFeatureFlags::useSharedAnimatedBackend();
 }
 
+bool NativeReactNativeFeatureFlags::useUnorderedMapInDifferentiator(
+    jsi::Runtime& /*runtime*/) {
+  return ReactNativeFeatureFlags::useUnorderedMapInDifferentiator();
+}
+
 bool NativeReactNativeFeatureFlags::useTraitHiddenOnAndroid(
     jsi::Runtime& /*runtime*/) {
   return ReactNativeFeatureFlags::useTraitHiddenOnAndroid();
diff --git a/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h b/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h
index bfb867589ab0..f1842ae9f09d 100644
--- a/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h
+++ b/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<2b82eb6d91d0b4437aa3b25f0488fe3e>>
+ * @generated SignedSource<<d14b7073e3fee31d0b1f1e08a70c87dd>>
  */
 
 /**
@@ -192,6 +192,8 @@ class NativeReactNativeFeatureFlags
 
   bool useSharedAnimatedBackend(jsi::Runtime& runtime);
 
+  bool useUnorderedMapInDifferentiator(jsi::Runtime& runtime);
+
   bool useTraitHiddenOnAndroid(jsi::Runtime& runtime);
 
   bool useTurboModuleInterop(jsi::Runtime& runtime);
diff --git a/packages/react-native/ReactCommon/react/renderer/animations/LayoutAnimationKeyFrameManager.cpp b/packages/react-native/ReactCommon/react/renderer/animations/LayoutAnimationKeyFrameManager.cpp
index 8abb96cfcb97..320bbfe0bcfc 100644
--- a/packages/react-native/ReactCommon/react/renderer/animations/LayoutAnimationKeyFrameManager.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/animations/LayoutAnimationKeyFrameManager.cpp
@@ -256,8 +256,7 @@ LayoutAnimationKeyFrameManager::pullTransaction(
       //   Catch delete+create (reparenting) (this should be optimized away at
       //   the diffing level eventually?)
       // TODO: to prevent this step we could tag Remove/Insert mutations as
-      // being moves on the Differ level, since we know that there? We could use
-      // TinyMap here, but it's not exposed by Differentiator (yet).
+      // being moves on the Differ level, since we know that there?
       std::unordered_set<Tag> insertedTags;
       std::unordered_set<Tag> deletedTags;
       std::unordered_set<Tag>
diff --git a/packages/react-native/ReactCommon/react/renderer/mounting/Differentiator.cpp b/packages/react-native/ReactCommon/react/renderer/mounting/Differentiator.cpp
index dff263a34981..d3c7c92376fd 100644
--- a/packages/react-native/ReactCommon/react/renderer/mounting/Differentiator.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/mounting/Differentiator.cpp
@@ -9,11 +9,10 @@
 
 #include <cxxreact/TraceSection.h>
 #include <react/debug/react_native_assert.h>
-#include <react/featureflags/ReactNativeFeatureFlags.h>
 #include <algorithm>
 #include "internal/CullingContext.h"
+#include "internal/DiffMap.h"
 #include "internal/ShadowViewNodePair.h"
-#include "internal/TinyMap.h"
 #include "internal/sliceChildShadowNodeViewPairs.h"
 
 #include "ShadowView.h"
@@ -58,7 +57,7 @@ static std::ostream& operator<<(
 
 #ifdef DEBUG_LOGS_DIFFER
 template <typename KeyT, typename ValueT>
-static std::ostream& operator<<(std::ostream& out, TinyMap<KeyT, ValueT>& map) {
+static std::ostream& operator<<(std::ostream& out, DiffMap<KeyT, ValueT>& map) {
   auto it = map.begin();
   if (it != map.end()) {
     out << *it->second;
@@ -143,7 +142,7 @@ struct OrderedMutationInstructionContainer {
 static void updateMatchedPairSubtrees(
     ViewNodePairScope& scope,
     OrderedMutationInstructionContainer& mutationContainer,
-    TinyMap<Tag, ShadowViewNodePair*>& newRemainingPairs,
+    DiffMap<Tag, ShadowViewNodePair*>& newRemainingPairs,
     std::vector<ShadowViewNodePair*>& oldChildPairs,
     Tag parentTag,
     const ShadowViewNodePair& oldPair,
@@ -164,11 +163,11 @@ static void calculateShadowViewMutationsFlattener(
     ReparentMode reparentMode,
     OrderedMutationInstructionContainer& mutationContainer,
     Tag parentTag,
-    TinyMap<Tag, ShadowViewNodePair*>& unvisitedOtherNodes,
+    DiffMap<Tag, ShadowViewNodePair*>& unvisitedOtherNodes,
     const ShadowViewNodePair& node,
     Tag parentTagForUpdate,
-    TinyMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherNewNodes,
-    TinyMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherOldNodes,
+    DiffMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherNewNodes,
+    DiffMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherOldNodes,
     const CullingContext& cullingContextForUnvisitedOtherNodes,
     const CullingContext& cullingContext);
 
@@ -183,7 +182,7 @@ static void calculateShadowViewMutationsFlattener(
 static void updateMatchedPairSubtrees(
     ViewNodePairScope& scope,
     OrderedMutationInstructionContainer& mutationContainer,
-    TinyMap<Tag, ShadowViewNodePair*>& newRemainingPairs,
+    DiffMap<Tag, ShadowViewNodePair*>& newRemainingPairs,
     std::vector<ShadowViewNodePair*>& oldChildPairs,
     Tag parentTag,
     const ShadowViewNodePair& oldPair,
@@ -232,7 +231,6 @@ static void updateMatchedPairSubtrees(
     // Unflattening
     else {
       // Construct unvisited nodes map
-      auto unvisitedOldChildPairs = TinyMap<Tag, ShadowViewNodePair*>{};
       // We don't know where all the children of oldChildPair are
       // within oldChildPairs, but we know that they're in the same
       // relative order. The reason for this is because of flattening
@@ -240,6 +238,8 @@ static void updateMatchedPairSubtrees(
       // interwoven with children from other nodes, etc.
       auto oldFlattenedNodes = sliceChildShadowNodeViewPairsFromViewNodePair(
           oldPair, scope, true, oldCullingContextCopy);
+      auto unvisitedOldChildPairs =
+          DiffMap<Tag, ShadowViewNodePair*>(oldFlattenedNodes.size());
       for (size_t i = 0, j = 0;
            i < oldChildPairs.size() && j < oldFlattenedNodes.size();
            i++) {
@@ -422,11 +422,11 @@ static void calculateShadowViewMutationsFlattener(
     ReparentMode reparentMode,
     OrderedMutationInstructionContainer& mutationContainer,
     Tag parentTag,
-    TinyMap<Tag, ShadowViewNodePair*>& unvisitedOtherNodes,
+    DiffMap<Tag, ShadowViewNodePair*>& unvisitedOtherNodes,
     const ShadowViewNodePair& node,
     Tag parentTagForUpdate,
-    TinyMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherNewNodes,
-    TinyMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherOldNodes,
+    DiffMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherNewNodes,
+    DiffMap<Tag, ShadowViewNodePair*>* parentSubVisitedOtherOldNodes,
     const CullingContext& cullingContextForUnvisitedOtherNodes,
     const CullingContext& cullingContext) {
   // Step 1: iterate through entire tree
@@ -445,8 +445,8 @@ static void calculateShadowViewMutationsFlattener(
 
   // Views in other tree that are visited by sub-flattening or
   // sub-unflattening
-  TinyMap<Tag, ShadowViewNodePair*> subVisitedOtherNewNodes{};
-  TinyMap<Tag, ShadowViewNodePair*> subVisitedOtherOldNodes{};
+  DiffMap<Tag, ShadowViewNodePair*> subVisitedOtherNewNodes{};
+  DiffMap<Tag, ShadowViewNodePair*> subVisitedOtherOldNodes{};
   auto subVisitedNewMap =
       (parentSubVisitedOtherNewNodes != nullptr ? parentSubVisitedOtherNewNodes
                                                 : &subVisitedOtherNewNodes);
@@ -456,7 +456,7 @@ static void calculateShadowViewMutationsFlattener(
 
   // Candidates for full tree creation or deletion at the end of this function
   auto deletionCreationCandidatePairs =
-      TinyMap<Tag, const ShadowViewNodePair*>{};
+      DiffMap<Tag, const ShadowViewNodePair*>(treeChildren.size());
 
   for (size_t index = 0;
        index < treeChildren.size() && index < treeChildren.size();
@@ -471,7 +471,7 @@ static void calculateShadowViewMutationsFlattener(
              : subVisitedNewMap->end());
     auto subVisitedOtherOldIt =
         (unvisitedIt == unvisitedOtherNodes.end() &&
-                 (subVisitedNewMap->end() != nullptr)
+                 subVisitedOtherNewIt == subVisitedNewMap->end()
              ? subVisitedOldMap->find(treeChildPair.shadowView.tag)
              : subVisitedOldMap->end());
 
@@ -697,7 +697,7 @@ static void calculateShadowViewMutationsFlattener(
                   : adjustedOldCullingContext);
           // Construct unvisited nodes map
           auto unvisitedRecursiveChildPairs =
-              TinyMap<Tag, ShadowViewNodePair*>{};
+              DiffMap<Tag, ShadowViewNodePair*>(flattenedNodes.size());
           for (auto& flattenedNode : flattenedNodes) {
             auto& newChild = *flattenedNode;
 
@@ -756,9 +756,6 @@ static void calculateShadowViewMutationsFlattener(
             // loop of this function.
             for (auto& unvisitedRecursiveChildPair :
                  unvisitedRecursiveChildPairs) {
-              if (unvisitedRecursiveChildPair.first == 0) {
-                continue;
-              }
               auto& oldFlattenedNode = *unvisitedRecursiveChildPair.second;
 
               // Node unvisited - mark the entire subtree for deletion
@@ -820,9 +817,6 @@ static void calculateShadowViewMutationsFlattener(
   // subtrees if they were never visited during the execution of the above
   // loop and recursions.
   for (auto& deletionCreationCandidatePair : deletionCreationCandidatePairs) {
-    if (deletionCreationCandidatePair.first == 0) {
-      continue;
-    }
     auto& treeChildPair = *deletionCreationCandidatePair.second;
 
     // If node was visited during a flattening/unflattening recursion,
@@ -1042,9 +1036,10 @@ static void calculateShadowViewMutations(
     }
   } else {
     // Collect map of tags in the new list
-    auto newRemainingPairs = TinyMap<Tag, ShadowViewNodePair*>{};
-    auto newInsertedPairs = TinyMap<Tag, ShadowViewNodePair*>{};
-    auto deletionCandidatePairs = TinyMap<Tag, const ShadowViewNodePair*>{};
+    auto remainingCount = newChildPairs.size() - index;
+    auto newRemainingPairs = DiffMap<Tag, ShadowViewNodePair*>(remainingCount);
+    auto newInsertedPairs = DiffMap<Tag, ShadowViewNodePair*>(remainingCount);
+    auto deletionCandidatePairs = DiffMap<Tag, const ShadowViewNodePair*>{};
     for (; index < newChildPairs.size(); index++) {
       auto& newChildPair = *newChildPairs[index];
       newRemainingPairs.insert({newChildPair.shadowView.tag, &newChildPair});
@@ -1243,10 +1238,6 @@ static void calculateShadowViewMutations(
     // list to make sure that a node was not reparented into an unflattened
     // node that occurs *after* it in the hierarchy, due to zIndex ordering.
     for (auto& deletionCandidatePair : deletionCandidatePairs) {
-      if (deletionCandidatePair.first == 0) {
-        continue;
-      }
-
       const auto& oldChildPair = *deletionCandidatePair.second;
 
       DEBUG_LOGS({
@@ -1285,14 +1276,6 @@ static void calculateShadowViewMutations(
     // Final step: generate Create instructions for entirely new
     // subtrees/nodes that are not the result of flattening or unflattening.
     for (auto& newInsertedPair : newInsertedPairs) {
-      // Erased elements of a TinyMap will have a Tag/key of 0 - skip those
-      // These *should* be removed by the map; there are currently no KNOWN
-      // cases where TinyMap will do the wrong thing, but there are not yet
-      // any unit tests explicitly for TinyMap, so this is safer for now.
-      if (newInsertedPair.first == 0) {
-        continue;
-      }
-
       const auto& newChildPair = *newInsertedPair.second;
 
       DEBUG_LOGS({
diff --git a/packages/react-native/ReactCommon/react/renderer/mounting/internal/DiffMap.h b/packages/react-native/ReactCommon/react/renderer/mounting/internal/DiffMap.h
new file mode 100644
index 000000000000..14e05f685f9e
--- /dev/null
+++ b/packages/react-native/ReactCommon/react/renderer/mounting/internal/DiffMap.h
@@ -0,0 +1,170 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <react/featureflags/ReactNativeFeatureFlags.h>
+#include <optional>
+#include <unordered_map>
+#include "TinyMap.h"
+
+namespace facebook::react {
+
+/**
+ * A facade that delegates to either TinyMap or std::unordered_map based on
+ * the useUnorderedMapInDifferentiator feature flag. This allows safe rollout
+ * of the unordered_map change in the Differentiator.
+ *
+ * Exposes a subset of the std::unordered_map interface used by the
+ * Differentiator: find, insert, erase, begin, end, and range-for.
+ *
+ * The Iterator returns const references because it uses a cached copy
+ * internally (the two backends have different pair types). The Differentiator
+ * only reads through iterators, never writes.
+ */
+template <typename KeyT, typename ValueT>
+class DiffMap final {
+ public:
+  using Pair = std::pair<KeyT, ValueT>;
+
+  class Iterator {
+   public:
+    const Pair &operator*() const
+    {
+      syncCached();
+      return cached_;
+    }
+
+    const Pair *operator->() const
+    {
+      syncCached();
+      return &cached_;
+    }
+
+    Iterator &operator++()
+    {
+      if (useUnorderedMap_) {
+        ++umIt_;
+      } else {
+        ++tinyIt_;
+      }
+      dirty_ = true;
+      return *this;
+    }
+
+    bool operator==(const Iterator &other) const
+    {
+      if (useUnorderedMap_) {
+        return umIt_ == other.umIt_;
+      }
+      return tinyIt_ == other.tinyIt_;
+    }
+
+    bool operator!=(const Iterator &other) const
+    {
+      return !(*this == other);
+    }
+
+   private:
+    friend class DiffMap;
+
+    void syncCached() const
+    {
+      if (!dirty_) {
+        return;
+      }
+      if (useUnorderedMap_) {
+        cached_ = {umIt_->first, umIt_->second};
+      } else {
+        cached_ = {tinyIt_->first, tinyIt_->second};
+      }
+      dirty_ = false;
+    }
+
+    bool useUnorderedMap_{false};
+    typename TinyMap<KeyT, ValueT>::Iterator tinyIt_{nullptr};
+    typename std::unordered_map<KeyT, ValueT>::iterator umIt_{};
+    mutable Pair cached_{};
+    mutable bool dirty_{true};
+  };
+
+  DiffMap() : useUnorderedMap_(ReactNativeFeatureFlags::useUnorderedMapInDifferentiator())
+  {
+    if (useUnorderedMap_) {
+      unorderedMap_.emplace();
+    }
+  }
+
+  explicit DiffMap(size_t sizeHint) : useUnorderedMap_(ReactNativeFeatureFlags::useUnorderedMapInDifferentiator())
+  {
+    if (useUnorderedMap_) {
+      unorderedMap_.emplace();
+      unorderedMap_->reserve(sizeHint);
+    }
+  }
+
+  Iterator begin()
+  {
+    Iterator it;
+    it.useUnorderedMap_ = useUnorderedMap_;
+    if (useUnorderedMap_) {
+      it.umIt_ = unorderedMap_->begin();
+    } else {
+      it.tinyIt_ = tinyMap_.begin();
+    }
+    return it;
+  }
+
+  Iterator end()
+  {
+    Iterator it;
+    it.useUnorderedMap_ = useUnorderedMap_;
+    if (useUnorderedMap_) {
+      it.umIt_ = unorderedMap_->end();
+    } else {
+      it.tinyIt_ = tinyMap_.end();
+    }
+    return it;
+  }
+
+  Iterator find(KeyT key)
+  {
+    Iterator it;
+    it.useUnorderedMap_ = useUnorderedMap_;
+    if (useUnorderedMap_) {
+      it.umIt_ = unorderedMap_->find(key);
+    } else {
+      it.tinyIt_ = tinyMap_.find(key);
+    }
+    return it;
+  }
+
+  void insert(Pair pair)
+  {
+    if (useUnorderedMap_) {
+      unorderedMap_->insert(std::move(pair));
+    } else {
+      tinyMap_.insert(std::move(pair));
+    }
+  }
+
+  void erase(Iterator it)
+  {
+    if (useUnorderedMap_) {
+      unorderedMap_->erase(it.umIt_);
+    } else {
+      tinyMap_.erase(it.tinyIt_);
+    }
+  }
+
+ private:
+  bool useUnorderedMap_;
+  TinyMap<KeyT, ValueT> tinyMap_;
+  std::optional<std::unordered_map<KeyT, ValueT>> unorderedMap_;
+};
+
+} // namespace facebook::react
diff --git a/packages/react-native/ReactCommon/react/renderer/mounting/internal/sliceChildShadowNodeViewPairs.h b/packages/react-native/ReactCommon/react/renderer/mounting/internal/sliceChildShadowNodeViewPairs.h
index 869da1d5de15..b85b1e13be46 100644
--- a/packages/react-native/ReactCommon/react/renderer/mounting/internal/sliceChildShadowNodeViewPairs.h
+++ b/packages/react-native/ReactCommon/react/renderer/mounting/internal/sliceChildShadowNodeViewPairs.h
@@ -18,10 +18,10 @@ struct ShadowViewNodePair;
 /**
  * During differ, we need to keep some `ShadowViewNodePair`s in memory.
  * Some `ShadowViewNodePair`s are referenced from std::vectors returned
- * by `sliceChildShadowNodeViewPairs`; some are referenced in TinyMaps
+ * by `sliceChildShadowNodeViewPairs`; some are referenced in maps
  * for view (un)flattening especially; and it is not always clear which
- * std::vectors will outlive which TinyMaps, and vice-versa, so it doesn't
- * make sense for the std::vector or TinyMap to own any `ShadowViewNodePair`s.
+ * std::vectors will outlive which maps, and vice-versa, so it doesn't
+ * make sense for the std::vector or map to own any `ShadowViewNodePair`s.
  *
  * Thus, we introduce the concept of a scope.
  *
diff --git a/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js b/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js
index e8e429ba609c..5f82807e57d8 100644
--- a/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js
+++ b/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js
@@ -880,6 +880,17 @@ const definitions: FeatureFlagDefinitions = {
       },
       ossReleaseStage: 'none',
     },
+    useUnorderedMapInDifferentiator: {
+      defaultValue: false,
+      metadata: {
+        dateAdded: '2026-02-26',
+        description:
+          'Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.',
+        expectedReleaseValue: true,
+        purpose: 'experimentation',
+      },
+      ossReleaseStage: 'none',
+    },
     useTraitHiddenOnAndroid: {
       defaultValue: false,
       metadata: {
diff --git a/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js b/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js
index 7939dec2f939..91958d900741 100644
--- a/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js
+++ b/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<fece18f7b3b23de103a64eca1a76a4c6>>
+ * @generated SignedSource<<c3f94597d4ed439b1d66ec4b23f86591>>
  * @flow strict
  * @noformat
  */
@@ -125,6 +125,7 @@ export type ReactNativeFeatureFlags = $ReadOnly<{
   useNativeViewConfigsInBridgelessMode: Getter<boolean>,
   useNestedScrollViewAndroid: Getter<boolean>,
   useSharedAnimatedBackend: Getter<boolean>,
+  useUnorderedMapInDifferentiator: Getter<boolean>,
   useTraitHiddenOnAndroid: Getter<boolean>,
   useTurboModuleInterop: Getter<boolean>,
   useTurboModules: Getter<boolean>,
@@ -509,6 +510,10 @@ export const useNestedScrollViewAndroid: Getter<boolean> = createNativeFlagGette
  * Use shared animation backend in C++ Animated
  */
 export const useSharedAnimatedBackend: Getter<boolean> = createNativeFlagGetter('useSharedAnimatedBackend', false);
+/**
+ * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+ */
+export const useUnorderedMapInDifferentiator: Getter<boolean> = createNativeFlagGetter('useUnorderedMapInDifferentiator', false);
 /**
  * Use Trait::hidden on Android
  */
diff --git a/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js b/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js
index 128f27b7f32e..06915d27c39f 100644
--- a/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js
+++ b/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js
@@ -4,7 +4,7 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  *
- * @generated SignedSource<<3495a8cf9d3d820e37d082b3d62e2b91>>
+ * @generated SignedSource<<907f8a9efe341ffb9cc8b81cb4e103b9>>
  * @flow strict
  * @noformat
  */
@@ -103,6 +103,7 @@ export interface Spec extends TurboModule {
   +useNativeViewConfigsInBridgelessMode?: () => boolean;
   +useNestedScrollViewAndroid?: () => boolean;
   +useSharedAnimatedBackend?: () => boolean;
+  +useUnorderedMapInDifferentiator?: () => boolean;
   +useTraitHiddenOnAndroid?: () => boolean;
   +useTurboModuleInterop?: () => boolean;
   +useTurboModules?: () => boolean;