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..a2295ba531ec 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<<156d4f5f35037184b6fc61ff1d856028>>
  */
 
 /**
@@ -516,6 +516,12 @@ public object ReactNativeFeatureFlags {
   @JvmStatic
   public fun useTurboModules(): Boolean = accessor.useTurboModules()
 
+  /**
+   * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+   */
+  @JvmStatic
+  public fun useUnorderedMapInDifferentiator(): Boolean = accessor.useUnorderedMapInDifferentiator()
+
   /**
    * Outset the culling context frame with the provided ratio. The culling context frame size will be outset by width * ratio on the left and right, and height * ratio on the top and bottom.
    */
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..df54de170654 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<<0875d5e54d884a26d37bb4eb2acc57d5>>
  */
 
 /**
@@ -101,6 +101,7 @@ internal class ReactNativeFeatureFlagsCxxAccessor : ReactNativeFeatureFlagsAcces
   private var useTraitHiddenOnAndroidCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
+  private var useUnorderedMapInDifferentiatorCache: Boolean? = null
   private var viewCullingOutsetRatioCache: Double? = null
   private var viewTransitionEnabledCache: Boolean? = null
   private var virtualViewPrerenderRatioCache: Double? = null
@@ -834,6 +835,15 @@ 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 viewCullingOutsetRatio(): Double {
     var cached = viewCullingOutsetRatioCache
     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..a9e7550867b7 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<<948a9beebe2ff00791a03455eb774eee>>
  */
 
 /**
@@ -190,6 +190,8 @@ public object ReactNativeFeatureFlagsCxxInterop {
 
   @DoNotStrip @JvmStatic public external fun useTurboModules(): Boolean
 
+  @DoNotStrip @JvmStatic public external fun useUnorderedMapInDifferentiator(): Boolean
+
   @DoNotStrip @JvmStatic public external fun viewCullingOutsetRatio(): Double
 
   @DoNotStrip @JvmStatic public external fun viewTransitionEnabled(): 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..b7e15d740909 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<<89c61520177334f93c65ff92c2fc74a6>>
  */
 
 /**
@@ -185,6 +185,8 @@ public open class ReactNativeFeatureFlagsDefaults : ReactNativeFeatureFlagsProvi
 
   override fun useTurboModules(): Boolean = false
 
+  override fun useUnorderedMapInDifferentiator(): Boolean = false
+
   override fun viewCullingOutsetRatio(): Double = 0.0
 
   override fun viewTransitionEnabled(): 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..48cb60dc5894 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<<669708c311abe9ffc8f7783219e2baad>>
  */
 
 /**
@@ -105,6 +105,7 @@ internal class ReactNativeFeatureFlagsLocalAccessor : ReactNativeFeatureFlagsAcc
   private var useTraitHiddenOnAndroidCache: Boolean? = null
   private var useTurboModuleInteropCache: Boolean? = null
   private var useTurboModulesCache: Boolean? = null
+  private var useUnorderedMapInDifferentiatorCache: Boolean? = null
   private var viewCullingOutsetRatioCache: Double? = null
   private var viewTransitionEnabledCache: Boolean? = null
   private var virtualViewPrerenderRatioCache: Double? = null
@@ -919,6 +920,16 @@ 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 viewCullingOutsetRatio(): Double {
     var cached = viewCullingOutsetRatioCache
     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..e0b05b9dde3c 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<<db06b64a8d1b9ab99b368fea41185d62>>
  */
 
 /**
@@ -185,6 +185,8 @@ public interface ReactNativeFeatureFlagsProvider {
 
   @DoNotStrip public fun useTurboModules(): Boolean
 
+  @DoNotStrip public fun useUnorderedMapInDifferentiator(): Boolean
+
   @DoNotStrip public fun viewCullingOutsetRatio(): Double
 
   @DoNotStrip public fun viewTransitionEnabled(): 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..7a60a11c7279 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<<0b95d68522d63d51d3e524aeecff246a>>
  */
 
 /**
@@ -525,6 +525,12 @@ class ReactNativeFeatureFlagsJavaProvider
     return method(javaProvider_);
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    static const auto method =
+        getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jboolean()>("useUnorderedMapInDifferentiator");
+    return method(javaProvider_);
+  }
+
   double viewCullingOutsetRatio() override {
     static const auto method =
         getReactNativeFeatureFlagsProviderJavaClass()->getMethod<jdouble()>("viewCullingOutsetRatio");
@@ -952,6 +958,11 @@ bool JReactNativeFeatureFlagsCxxInterop::useTurboModules(
   return ReactNativeFeatureFlags::useTurboModules();
 }
 
+bool JReactNativeFeatureFlagsCxxInterop::useUnorderedMapInDifferentiator(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
+  return ReactNativeFeatureFlags::useUnorderedMapInDifferentiator();
+}
+
 double JReactNativeFeatureFlagsCxxInterop::viewCullingOutsetRatio(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop> /*unused*/) {
   return ReactNativeFeatureFlags::viewCullingOutsetRatio();
@@ -1241,6 +1252,9 @@ void JReactNativeFeatureFlagsCxxInterop::registerNatives() {
       makeNativeMethod(
         "useTurboModules",
         JReactNativeFeatureFlagsCxxInterop::useTurboModules),
+      makeNativeMethod(
+        "useUnorderedMapInDifferentiator",
+        JReactNativeFeatureFlagsCxxInterop::useUnorderedMapInDifferentiator),
       makeNativeMethod(
         "viewCullingOutsetRatio",
         JReactNativeFeatureFlagsCxxInterop::viewCullingOutsetRatio),
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..67889af8a636 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<<6b7e2af51ba9d64ae4e474dfa104a7c3>>
  */
 
 /**
@@ -273,6 +273,9 @@ class JReactNativeFeatureFlagsCxxInterop
   static bool useTurboModules(
     facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
 
+  static bool useUnorderedMapInDifferentiator(
+    facebook::jni::alias_ref<JReactNativeFeatureFlagsCxxInterop>);
+
   static double viewCullingOutsetRatio(
     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..0c045bcf92d2 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<<08a361f2ffac6a0496adac1d4c3e4726>>
  */
 
 /**
@@ -350,6 +350,10 @@ bool ReactNativeFeatureFlags::useTurboModules() {
   return getAccessor().useTurboModules();
 }
 
+bool ReactNativeFeatureFlags::useUnorderedMapInDifferentiator() {
+  return getAccessor().useUnorderedMapInDifferentiator();
+}
+
 double ReactNativeFeatureFlags::viewCullingOutsetRatio() {
   return getAccessor().viewCullingOutsetRatio();
 }
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlags.h
index 8a1ca2766b22..af8e15b1e6ed 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<<0bbe4d41581432dfad7adbc2db133d00>>
  */
 
 /**
@@ -444,6 +444,11 @@ class ReactNativeFeatureFlags {
    */
   RN_EXPORT static bool useTurboModules();
 
+  /**
+   * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+   */
+  RN_EXPORT static bool useUnorderedMapInDifferentiator();
+
   /**
    * Outset the culling context frame with the provided ratio. The culling context frame size will be outset by width * ratio on the left and right, and height * ratio on the top and bottom.
    */
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsAccessor.cpp
index aafd52dd5889..de6c64c0be12 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<<3dd9492ca660ad6350ce6ee4a9b5e310>>
  */
 
 /**
@@ -1487,6 +1487,24 @@ bool ReactNativeFeatureFlagsAccessor::useTurboModules() {
   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(81, "useUnorderedMapInDifferentiator");
+
+    flagValue = currentProvider_->useUnorderedMapInDifferentiator();
+    useUnorderedMapInDifferentiator_ = flagValue;
+  }
+
+  return flagValue.value();
+}
+
 double ReactNativeFeatureFlagsAccessor::viewCullingOutsetRatio() {
   auto flagValue = viewCullingOutsetRatio_.load();
 
@@ -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..b3784c81fe63 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<<2cb2c124f044468f96262086bfac5aad>>
  */
 
 /**
@@ -113,6 +113,7 @@ class ReactNativeFeatureFlagsAccessor {
   bool useTraitHiddenOnAndroid();
   bool useTurboModuleInterop();
   bool useTurboModules();
+  bool useUnorderedMapInDifferentiator();
   double viewCullingOutsetRatio();
   bool viewTransitionEnabled();
   double virtualViewPrerenderRatio();
@@ -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_;
@@ -210,6 +211,7 @@ class ReactNativeFeatureFlagsAccessor {
   std::atomic<std::optional<bool>> useTraitHiddenOnAndroid_;
   std::atomic<std::optional<bool>> useTurboModuleInterop_;
   std::atomic<std::optional<bool>> useTurboModules_;
+  std::atomic<std::optional<bool>> useUnorderedMapInDifferentiator_;
   std::atomic<std::optional<double>> viewCullingOutsetRatio_;
   std::atomic<std::optional<bool>> viewTransitionEnabled_;
   std::atomic<std::optional<double>> virtualViewPrerenderRatio_;
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDefaults.h
index e17c94e91f53..75ba8e143e40 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<<7f1c4037925fc37dcdcba51df968d503>>
  */
 
 /**
@@ -351,6 +351,10 @@ class ReactNativeFeatureFlagsDefaults : public ReactNativeFeatureFlagsProvider {
     return false;
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    return false;
+  }
+
   double viewCullingOutsetRatio() override {
     return 0.0;
   }
diff --git a/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h b/packages/react-native/ReactCommon/react/featureflags/ReactNativeFeatureFlagsDynamicProvider.h
index 56c0e084c0f9..62a9247ac77d 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<<db6a2d2e1d96e088574d91ae2825fe5e>>
  */
 
 /**
@@ -774,6 +774,15 @@ class ReactNativeFeatureFlagsDynamicProvider : public ReactNativeFeatureFlagsDef
     return ReactNativeFeatureFlagsDefaults::useTurboModules();
   }
 
+  bool useUnorderedMapInDifferentiator() override {
+    auto value = values_["useUnorderedMapInDifferentiator"];
+    if (!value.isNull()) {
+      return value.getBool();
+    }
+
+    return ReactNativeFeatureFlagsDefaults::useUnorderedMapInDifferentiator();
+  }
+
   double viewCullingOutsetRatio() override {
     auto value = values_["viewCullingOutsetRatio"];
     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..f1cff605711a 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<<43e301c5028a2ed195e2a3d0a4cd0ab3>>
  */
 
 /**
@@ -106,6 +106,7 @@ class ReactNativeFeatureFlagsProvider {
   virtual bool useTraitHiddenOnAndroid() = 0;
   virtual bool useTurboModuleInterop() = 0;
   virtual bool useTurboModules() = 0;
+  virtual bool useUnorderedMapInDifferentiator() = 0;
   virtual double viewCullingOutsetRatio() = 0;
   virtual bool viewTransitionEnabled() = 0;
   virtual double virtualViewPrerenderRatio() = 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..34101508393f 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<<006c43555032f785207c6c013f1974f5>>
  */
 
 /**
@@ -449,6 +449,11 @@ bool NativeReactNativeFeatureFlags::useTurboModules(
   return ReactNativeFeatureFlags::useTurboModules();
 }
 
+bool NativeReactNativeFeatureFlags::useUnorderedMapInDifferentiator(
+    jsi::Runtime& /*runtime*/) {
+  return ReactNativeFeatureFlags::useUnorderedMapInDifferentiator();
+}
+
 double NativeReactNativeFeatureFlags::viewCullingOutsetRatio(
     jsi::Runtime& /*runtime*/) {
   return ReactNativeFeatureFlags::viewCullingOutsetRatio();
diff --git a/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h b/packages/react-native/ReactCommon/react/nativemodule/featureflags/NativeReactNativeFeatureFlags.h
index bfb867589ab0..6675417c0e51 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<<525d64b15e1b72440743363280116c6a>>
  */
 
 /**
@@ -198,6 +198,8 @@ class NativeReactNativeFeatureFlags
 
   bool useTurboModules(jsi::Runtime& runtime);
 
+  bool useUnorderedMapInDifferentiator(jsi::Runtime& runtime);
+
   double viewCullingOutsetRatio(jsi::Runtime& runtime);
 
   bool viewTransitionEnabled(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..04154d728767 100644
--- a/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js
+++ b/packages/react-native/scripts/featureflags/ReactNativeFeatureFlags.config.js
@@ -911,6 +911,17 @@ const definitions: FeatureFlagDefinitions = {
       },
       ossReleaseStage: 'canary',
     },
+    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',
+    },
     viewCullingOutsetRatio: {
       defaultValue: 0,
       metadata: {
diff --git a/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js b/packages/react-native/src/private/featureflags/ReactNativeFeatureFlags.js
index 7939dec2f939..e2e66482fde4 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<<8cd3151384989b1a4e8ec204943e2435>>
  * @flow strict
  * @noformat
  */
@@ -128,6 +128,7 @@ export type ReactNativeFeatureFlags = $ReadOnly<{
   useTraitHiddenOnAndroid: Getter<boolean>,
   useTurboModuleInterop: Getter<boolean>,
   useTurboModules: Getter<boolean>,
+  useUnorderedMapInDifferentiator: Getter<boolean>,
   viewCullingOutsetRatio: Getter<number>,
   viewTransitionEnabled: Getter<boolean>,
   virtualViewPrerenderRatio: Getter<number>,
@@ -521,6 +522,10 @@ export const useTurboModuleInterop: Getter<boolean> = createNativeFlagGetter('us
  * When enabled, NativeModules will be executed by using the TurboModule system
  */
 export const useTurboModules: Getter<boolean> = createNativeFlagGetter('useTurboModules', false);
+/**
+ * Use std::unordered_map instead of TinyMap in the Differentiator for improved lookup performance.
+ */
+export const useUnorderedMapInDifferentiator: Getter<boolean> = createNativeFlagGetter('useUnorderedMapInDifferentiator', false);
 /**
  * Outset the culling context frame with the provided ratio. The culling context frame size will be outset by width * ratio on the left and right, and height * ratio on the top and bottom.
  */
diff --git a/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js b/packages/react-native/src/private/featureflags/specs/NativeReactNativeFeatureFlags.js
index 128f27b7f32e..4b47cc872f5c 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<<2955ab3f744af8b5cdf587312ba423d7>>
  * @flow strict
  * @noformat
  */
@@ -106,6 +106,7 @@ export interface Spec extends TurboModule {
   +useTraitHiddenOnAndroid?: () => boolean;
   +useTurboModuleInterop?: () => boolean;
   +useTurboModules?: () => boolean;
+  +useUnorderedMapInDifferentiator?: () => boolean;
   +viewCullingOutsetRatio?: () => number;
   +viewTransitionEnabled?: () => boolean;
   +virtualViewPrerenderRatio?: () => number;