diff --git a/src/provider/OptimizelyProvider.spec.tsx b/src/provider/OptimizelyProvider.spec.tsx
index d24030c..b2cb304 100644
--- a/src/provider/OptimizelyProvider.spec.tsx
+++ b/src/provider/OptimizelyProvider.spec.tsx
@@ -228,7 +228,7 @@ describe('OptimizelyProvider', () => {
   });
 
   describe('cleanup', () => {
-    it('should reset store on unmount', async () => {
+    it('should not reset store on unmount (store becomes unreachable to React tree)', async () => {
       const mockClient = createMockClient();
       let capturedContext: OptimizelyContextValue | null = null;
 
@@ -246,8 +246,11 @@ describe('OptimizelyProvider', () => {
 
       unmount();
 
-      // Store should be reset
-      expect(store.getState().userContext).toBeNull();
+      // Store state is preserved — on real unmount, the store becomes
+      // unreachable to the React tree. Eagerly resetting breaks React
+      // 18+ StrictMode (effect cleanup destroys state that the render
+      // body set, and no re-render restores it).
+      expect(store.getState().userContext).not.toBeNull();
       expect(store.getState().error).toBeNull();
     });
   });
@@ -391,7 +394,7 @@ describe('OptimizelyProvider', () => {
       expect(mockClient2.createUserContext).toHaveBeenCalledWith('user-1', undefined);
     });
 
-    it('should dispose manager on unmount', async () => {
+    it('should preserve store state on unmount (no eager reset)', async () => {
       const mockClient = createMockClient();
       let capturedContext: OptimizelyContextValue | null = null;
 
@@ -406,8 +409,9 @@ describe('OptimizelyProvider', () => {
 
       unmount();
 
-      // Store should be reset after unmount
-      expect(capturedContext!.store.getState().userContext).toBeNull();
+      // Store state is preserved after unmount — no eager reset.
+      // The store becomes unreachable to the React tree.
+      expect(capturedContext!.store.getState().userContext).not.toBeNull();
     });
 
     it('should recreate user context when only attributes change (same id)', async () => {
diff --git a/src/provider/OptimizelyProvider.tsx b/src/provider/OptimizelyProvider.tsx
index eeb5027..3d24001 100644
--- a/src/provider/OptimizelyProvider.tsx
+++ b/src/provider/OptimizelyProvider.tsx
@@ -38,6 +38,7 @@ export function OptimizelyProvider({
   const storeRef = useRef<ProviderStateStore | null>(null);
   const userManagerRef = useRef<UserContextManager | null>(null);
   const prevClientRef = useRef<Client>();
+  const hadConfigAtRender = useMemo(() => !!client?.getOptimizelyConfig(), [client]);
 
   if (storeRef.current === null) {
     storeRef.current = new ProviderStateStore();
@@ -70,8 +71,8 @@ export function OptimizelyProvider({
     userManagerRef.current.resolveUserContext(user, qualifiedSegments, skipSegments);
   }
 
-  // Effect: Client onReady — only needed for error handling.
-  // Readiness is derived from userContext + getOptimizelyConfig() by hooks.
+  // Effect: Client readiness + config update subscription.
+  // Handles both initial datafile fetch and subsequent polling updates.
   useEffect(() => {
     if (!client) {
       console.error('[OPTIMIZELY - REACT] OptimizelyProvider must be passed an Optimizely client instance');
@@ -80,42 +81,38 @@ export function OptimizelyProvider({
     }
 
     let isMounted = true;
-
-    client.onReady({ timeout }).catch((error) => {
-      if (!isMounted) return;
-      const err = error instanceof Error ? error : new Error(String(error));
-      store.setError(err);
-    });
-
-    return () => {
-      isMounted = false;
-    };
-  }, [client, timeout, store]);
-
-  // Effect: Subscribe to config/datafile updates (e.g., polling)
-  useEffect(() => {
-    if (!client) return;
+    // When the datafile response is cached (e.g. browser HTTP cache),
+    // CONFIG_UPDATE may fire before this effect subscribes. In that case
+    // onReady resolves but CONFIG_UPDATE is never re-emitted (config
+    // didn't change). The flag lets onReady act as a fallback without
+    // causing a double-refresh when both fire.
+    let configReceived = false;
 
     const listenerId = client.notificationCenter.addNotificationListener(
       NOTIFICATION_TYPES.OPTIMIZELY_CONFIG_UPDATE,
       () => {
+        configReceived = true;
         store.refresh();
       }
     );
 
-    return () => {
-      client.notificationCenter.removeNotificationListener(listenerId);
-    };
-  }, [client, store]);
+    client
+      .onReady({ timeout })
+      .then(() => {
+        if (!isMounted || configReceived || hadConfigAtRender) return;
+        store.refresh();
+      })
+      .catch((error) => {
+        if (!isMounted) return;
+        const err = error instanceof Error ? error : new Error(String(error));
+        store.setError(err);
+      });
 
-  // Cleanup on unmount
-  useEffect(() => {
     return () => {
-      userManagerRef.current?.dispose();
-      userManagerRef.current = null;
-      store.reset();
+      isMounted = false;
+      client.notificationCenter.removeNotificationListener(listenerId);
     };
-  }, [store]);
+  }, [client, timeout, store, hadConfigAtRender]);
 
   return <OptimizelyContext.Provider value={contextValue}>{children}</OptimizelyContext.Provider>;
 }