Skip View prop transforms when no transformed props are passed

View copies its props and checks 17 keys on every render to map aria-*,
id and tabIndex onto their native equivalents. Most Views pass none of
them, so check first and pass props through unchanged in that case.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Author: shubh73

packages/react-native/Libraries/Components/View/View.js

@@ -39,6 +39,64 @@ export type ViewInstance = HostInstance;
 component View(ref?: React.RefSetter<ViewInstance>, ...props: ViewProps) {
   const hasTextAncestor = use(TextAncestorContext);
 
+  // Fast path: most views use none of the props that need transforming, so
+  // skip copying and rewriting their props.
+  let resolvedProps = needsPropTransforms(props)
+    ? transformProps(props)
+    : props;
+
+  if (__DEV__) {
+    const onSafeAreaInsetsChange =
+      resolvedProps.experimental_onSafeAreaInsetsChange;
+    if (onSafeAreaInsetsChange != null) {
+      // Copy rather than assign: on the fast path this is the incoming props.
+      resolvedProps = {
+        ...resolvedProps,
+        experimental_onSafeAreaInsetsChange:
+          warnOnRepeatedSafeAreaInsetsChanges(onSafeAreaInsetsChange),
+      };
+    }
+  }
+
+  const actualView =
+    ref == null ? (
+      <ViewNativeComponent {...resolvedProps} />
+    ) : (
+      <ViewNativeComponent {...resolvedProps} ref={ref} />
+    );
+
+  if (hasTextAncestor) {
+    return (
+      <TextAncestorContext value={false}>{actualView}</TextAncestorContext>
+    );
+  }
+  return actualView;
+}
+
+// Must check every prop that `transformProps` reads.
+function needsPropTransforms(props: ViewProps): boolean {
+  return (
+    props.accessibilityState !== undefined ||
+    props.accessibilityValue !== undefined ||
+    props['aria-busy'] !== undefined ||
+    props['aria-checked'] !== undefined ||
+    props['aria-disabled'] !== undefined ||
+    props['aria-expanded'] !== undefined ||
+    props['aria-hidden'] !== undefined ||
+    props['aria-label'] !== undefined ||
+    props['aria-labelledby'] !== undefined ||
+    props['aria-live'] !== undefined ||
+    props['aria-selected'] !== undefined ||
+    props['aria-valuemax'] !== undefined ||
+    props['aria-valuemin'] !== undefined ||
+    props['aria-valuenow'] !== undefined ||
+    props['aria-valuetext'] !== undefined ||
+    props.id !== undefined ||
+    props.tabIndex !== undefined
+  );
+}
+
+function transformProps(props: ViewProps): ViewProps {
   const {
     accessibilityState,
     accessibilityValue,
@@ -123,28 +181,7 @@ component View(ref?: React.RefSetter<ViewInstance>, ...props: ViewProps) {
     };
   }
 
-  if (__DEV__) {
-    const onSafeAreaInsetsChange =
-      resolvedProps.experimental_onSafeAreaInsetsChange;
-    if (onSafeAreaInsetsChange != null) {
-      resolvedProps.experimental_onSafeAreaInsetsChange =
-        warnOnRepeatedSafeAreaInsetsChanges(onSafeAreaInsetsChange);
-    }
-  }
-
-  const actualView =
-    ref == null ? (
-      <ViewNativeComponent {...resolvedProps} />
-    ) : (
-      <ViewNativeComponent {...resolvedProps} ref={ref} />
-    );
-
-  if (hasTextAncestor) {
-    return (
-      <TextAncestorContext value={false}>{actualView}</TextAncestorContext>
-    );
-  }
-  return actualView;
+  return resolvedProps;
 }
 
 View.displayName = 'View';

packages/react-native/Libraries/Components/View/__tests__/View-propTransforms-benchmark-itest.js

@@ -0,0 +1,110 @@
+/**
+ * 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.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
+
+import measureRenderTime from '../../../../src/private/__tests__/utilities/measureRenderTime';
+import * as Fantom from '@react-native/fantom';
+import * as React from 'react';
+import {View} from 'react-native';
+
+const COUNT = 100;
+
+let root: Fantom.Root;
+let initial: React.MixedElement;
+let next: React.MixedElement;
+
+type Variant = Readonly<{
+  name: string,
+  update: boolean,
+  render: (i: number, gen: number) => React.Node,
+}>;
+
+const variants: ReadonlyArray<Variant> = [
+  {
+    name: 'mount, plain (fast path)',
+    update: false,
+    render: i => <View key={i} style={{width: i + 1, height: 1}} />,
+  },
+  {
+    name: 'update, plain (fast path)',
+    update: true,
+    render: (i, gen) => <View key={i} style={{width: i + gen, height: 1}} />,
+  },
+  {
+    name: 'mount, testID + pointerEvents (fast path)',
+    update: false,
+    render: i => (
+      <View
+        key={i}
+        testID={'v' + i}
+        pointerEvents="box-none"
+        style={{width: i + 1, height: 1}}
+      />
+    ),
+  },
+  {
+    name: 'mount, aria-label (slow path)',
+    update: false,
+    render: i => (
+      <View key={i} aria-label={'v' + i} style={{width: i + 1, height: 1}} />
+    ),
+  },
+  {
+    name: 'update, aria-label (slow path)',
+    update: true,
+    render: (i, gen) => (
+      <View key={i} aria-label={'v' + i} style={{width: i + gen, height: 1}} />
+    ),
+  },
+  {
+    name: 'mount, accessibilityState (slow path, like Pressable)',
+    update: false,
+    render: i => (
+      <View
+        key={i}
+        accessibilityState={{disabled: false}}
+        style={{width: i + 1, height: 1}}
+      />
+    ),
+  },
+];
+
+function build(variant: Variant, gen: number): React.MixedElement {
+  const children = [];
+  for (let i = 0; i < COUNT; i++) {
+    children.push(variant.render(i, gen));
+  }
+  return <>{children}</>;
+}
+
+Fantom.unstable_benchmark
+  .suite('View prop transforms', {minIterations: 1000})
+  .test.each(
+    variants,
+    variant => `${variant.name}, ${COUNT} views`,
+    () => ({overriddenDuration: measureRenderTime(root, next)}),
+    variant => ({
+      beforeAll: () => {
+        initial = build(variant, 1);
+        next = variant.update ? build(variant, 2) : initial;
+      },
+      beforeEach: () => {
+        root = Fantom.createRoot();
+        if (variant.update) {
+          // Same wrapper as the measured render, so React updates in place.
+          measureRenderTime(root, initial);
+        }
+      },
+      afterEach: () => {
+        root.destroy();
+      },
+    }),
+  );