diff --git a/packages/react-native/src/private/webapis/performance/__tests__/EventTimingAPI-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/EventTimingAPI-itest.js
index 5c46106f95d..886a5da8481 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/EventTimingAPI-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/EventTimingAPI-itest.js
@@ -10,24 +10,17 @@
 
 import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
-import type Performance from 'react-native/src/private/webapis/performance/Performance';
-import type {PerformanceObserverEntryList} from 'react-native/src/private/webapis/performance/PerformanceObserver';
-
 import MaybeNativePerformance from '../specs/NativePerformance';
 import * as Fantom from '@react-native/fantom';
 import nullthrows from 'nullthrows';
 import {useState} from 'react';
 import {Text, View} from 'react-native';
 import setUpPerformanceObserver from 'react-native/src/private/setup/setUpPerformanceObserver';
-import {PerformanceEventTiming} from 'react-native/src/private/webapis/performance/EventTiming';
-import {PerformanceObserver} from 'react-native/src/private/webapis/performance/PerformanceObserver';
 
 const NativePerformance = nullthrows(MaybeNativePerformance);
 
 setUpPerformanceObserver();
 
-declare var performance: Performance;
-
 function sleep(ms: number) {
   const end = performance.now() + ms;
   while (performance.now() < end) {}
diff --git a/packages/react-native/src/private/webapis/performance/__tests__/LongTasksAPI-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/LongTasksAPI-itest.js
index 80ff9cf54f0..990663ff03b 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/LongTasksAPI-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/LongTasksAPI-itest.js
@@ -10,15 +10,10 @@
 
 import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
-import type {
-  PerformanceObserverCallbackOptions,
-  PerformanceObserverEntryList,
-} from 'react-native/src/private/webapis/performance/PerformanceObserver';
+import type {PerformanceObserverCallbackOptions} from '../PerformanceObserver';
 
 import * as Fantom from '@react-native/fantom';
 import setUpPerformanceObserver from 'react-native/src/private/setup/setUpPerformanceObserver';
-import {PerformanceLongTaskTiming} from 'react-native/src/private/webapis/performance/LongTasks';
-import {PerformanceObserver} from 'react-native/src/private/webapis/performance/PerformanceObserver';
 
 setUpPerformanceObserver();
 
diff --git a/packages/react-native/src/private/webapis/performance/__tests__/Performance-benchmark-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/Performance-benchmark-itest.js
index d69768d8d71..2829b8f94cf 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/Performance-benchmark-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/Performance-benchmark-itest.js
@@ -10,12 +10,8 @@
 
 import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
-import type Performance from 'react-native/src/private/webapis/performance/Performance';
-
 import * as Fantom from '@react-native/fantom';
 
-declare var performance: Performance;
-
 const clearMarksAndMeasures = () => {
   performance.clearMarks();
   performance.clearMeasures();
diff --git a/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
index c3c65486e34..77af8cb8c83 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/PerformanceObserver-itest.js
@@ -10,20 +10,11 @@
 
 import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
-import type Performance from '../Performance';
-import type {
-  PerformanceObserver as PerformanceObserverT,
-  PerformanceObserverEntryList,
-} from '../PerformanceObserver';
-
 import setUpPerformanceObserver from '../../../setup/setUpPerformanceObserver';
 import * as Fantom from '@react-native/fantom';
 
 setUpPerformanceObserver();
 
-declare var performance: Performance;
-declare var PerformanceObserver: Class<PerformanceObserverT>;
-
 describe('PerformanceObserver', () => {
   it('receives notifications for marks and measures', () => {
     const callback = jest.fn();
diff --git a/packages/react-native/src/private/webapis/performance/__tests__/UserTiming-itest.js b/packages/react-native/src/private/webapis/performance/__tests__/UserTiming-itest.js
index 0bc20e7c012..00714de389f 100644
--- a/packages/react-native/src/private/webapis/performance/__tests__/UserTiming-itest.js
+++ b/packages/react-native/src/private/webapis/performance/__tests__/UserTiming-itest.js
@@ -10,18 +10,12 @@
 
 import '@react-native/fantom/src/setUpDefaultReactNativeEnvironment';
 
-import type Performance from '../Performance';
-import type {
-  PerformanceEntryJSON,
-  PerformanceEntryList,
-} from '../PerformanceEntry';
-
 import ensureInstance from '../../../__tests__/utilities/ensureInstance';
+import setUpPerformanceObserver from '../../../setup/setUpPerformanceObserver';
 import DOMException from '../../errors/DOMException';
-import {PerformanceMark, PerformanceMeasure} from '../UserTiming';
 import * as Fantom from '@react-native/fantom';
 
-declare var performance: Performance;
+setUpPerformanceObserver();
 
 function getThrownError(fn: () => mixed): mixed {
   try {
@@ -32,7 +26,7 @@ function getThrownError(fn: () => mixed): mixed {
   throw new Error('Expected function to throw');
 }
 
-function toJSON(entries: PerformanceEntryList): Array<PerformanceEntryJSON> {
+function toJSON(entries: PerformanceEntryList): Array<mixed> {
   return entries.map(entry => entry.toJSON());
 }