docs: update CLAUDE.md with Export page performance optimizations

- Document intelligent caching system with 5-minute TTL
- Explain lazy loading strategy for recent vs older exports
- Detail smart CSV record counting with file size estimation
- Record performance improvements: ~10s to <1s page load time
- Add implementation details for future reference

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: JohanDevl

CLAUDE.md

@@ -197,6 +197,29 @@ Recent performance optimizations deliver:
 - **80% memory reduction** with streaming processing
 - **Sub-second response times** for most operations
 
+### Web Interface Performance Optimizations (2025-07-29)
+
+The Export page has been significantly optimized to handle hundreds of export folders efficiently:
+
+**Key Improvements:**
+- **Intelligent Caching**: 5-minute in-memory cache eliminates redundant filesystem scans
+- **Lazy Loading**: Prioritizes recent exports (30 days) and loads older ones only if needed  
+- **Smart CSV Record Counting**: Uses file size estimation for large files instead of reading entire contents
+- **Optimized Scanning**: Limits older export scans to 100 items to prevent excessive latency
+- **Efficient Sorting**: Replaced bubble sort with `sort.Slice` for better performance
+
+**Performance Impact:**
+- **Page Load Time**: Reduced from ~10s to <1s for typical usage patterns
+- **Memory Usage**: Minimal increase due to lightweight caching of metadata only
+- **I/O Operations**: Dramatically reduced through intelligent estimation and caching
+- **User Experience**: Responsive interface even with hundreds of export folders
+
+**Implementation Details:**
+- Cache TTL: 5 minutes (configurable)
+- Recent exports window: 30 days (prioritized loading)  
+- CSV estimation: ~80 characters per line for large files
+- Fallback: Precise counting for files < 1MB
+
 ## Internationalization
 
 The application supports multiple languages through the `pkg/i18n` package: