perf: add lazy loading for heavy components

- Use React.lazy for DataGrid, WeeklyGrid, and TopMovers
- Add Suspense with LoadingSpinner fallback for smooth transitions
- Enables code splitting for faster initial page load
- Combined with previous O(n²) fix, should significantly improve performance

App.tsx

@@ -1,11 +1,7 @@
 
-import React, { useState, useMemo, useEffect, useCallback } from 'react';
+import React, { useState, useMemo, useEffect, useCallback, Suspense, lazy } from 'react';
 import FileUpload from './components/FileUpload';
 import Dashboard from './components/Dashboard';
-import DataGrid from './components/DataGrid';
-import WeeklyGrid from './components/WeeklyGrid';
-import TopMovers from './components/TopMovers';
-// import AdvertisingDashboard from './components/AdvertisingDashboard'; // Removed
 import FilterBar from './components/FilterBar';
 import AIChat from './components/AIChat';
 import CrazeLogo from './components/CrazeLogo';
@@ -15,6 +11,18 @@ import { queryGemini } from './services/geminiService';
 import { ChartIcon, TableIcon, UploadIcon, DownloadIcon, CloseIcon, TrendingIcon } from './components/Icons';
 import { loadSalesData, saveSalesData, clearSalesData, loadAdsData, saveAdsData, clearAdsData } from './services/storage';
 
+// Lazy load heavy components for better initial performance
+const DataGrid = lazy(() => import('./components/DataGrid'));
+const WeeklyGrid = lazy(() => import('./components/WeeklyGrid'));
+const TopMovers = lazy(() => import('./components/TopMovers'));
+
+// Loading fallback component
+const LoadingSpinner = () => (
+  <div className="flex items-center justify-center h-96">
+    <div className="animate-spin rounded-full h-12 w-12 border-t-2 border-b-2 border-indigo-500"></div>
+  </div>
+);
+
 // New Refresh Icon
 const RefreshIcon = ({ className }: { className?: string }) => (
   <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" strokeWidth={1.5} stroke="currentColor" className={className || "w-5 h-5"}>
@@ -417,9 +425,11 @@ const App: React.FC = () => {
                   adsData={filteredAdsData}
                 />
               )}
-              {view === 'table' && <DataGrid data={combinedAdsData} hasCustomerFilter={filters.customer.length > 0} adsData={filteredAdsData} />}
+              <Suspense fallback={<LoadingSpinner />}>
-              {view === 'weekly' && <WeeklyGrid data={combinedAdsData} />}
+                {view === 'table' && <DataGrid data={combinedAdsData} hasCustomerFilter={filters.customer.length > 0} adsData={filteredAdsData} />}
-              {view === 'movers' && <TopMovers data={filteredData} />}
+                {view === 'weekly' && <WeeklyGrid data={combinedAdsData} />}
+                {view === 'movers' && <TopMovers data={filteredData} />}
+              </Suspense>
             </div>
           </>
         )}