perf(monitor): skip metadata-only map work

vehicle-data-platform/apps/web/src/v2/map/FleetMap.test.tsx

@@ -248,6 +248,33 @@ test('skips unchanged refresh redraws and replaces only a moved vehicle label',
   expect((replacementLabels[0].options.text as { content: string }).content).toBe('粤A12345');
 });
 
+test('does not traverse unchanged point arrays for an asOf-only refresh', async () => {
+  window.__LINGNIU_APP_CONFIG__ = { amapWebJsKey: 'amap-web-key' };
+  window.AMapLoader = { load: vi.fn(async () => amapMock()) };
+  let pointReads = 0;
+  const observedPoints = new Proxy(pointMap.points, {
+    get(target, property, receiver) {
+      if (typeof property === 'string' && /^\d+$/.test(property)) pointReads += 1;
+      return Reflect.get(target, property, receiver);
+    }
+  });
+  const observedMap = { ...pointMap, points: observedPoints };
+  const view = render(<FleetMap vehicles={[]} monitorMap={observedMap} onSelect={() => undefined} />);
+  await waitFor(() => expect(addLabels).toHaveBeenCalled());
+  pointReads = 0;
+
+  await act(async () => {
+    view.rerender(<FleetMap
+      vehicles={[]}
+      monitorMap={{ ...observedMap, asOf: '2026-07-14T01:00:15Z' }}
+      onSelect={() => undefined}
+    />);
+    await Promise.resolve();
+  });
+
+  expect(pointReads).toBe(0);
+});
+
 test('converts AMap GCJ-02 bounds back to WGS-84 before requesting monitor data', async () => {
   const [west, south] = wgs84ToGcj02(113, 22);
   const [east, north] = wgs84ToGcj02(114, 24);