v0.1.28 - CSV Performance Optimization

🚀 Performance Improvements

CSV Export Optimization (83-87% faster)

• Pre-allocated String buffers - Eliminates reallocations during CSV generation
• Replaced format!() with write!() - Reduces ~1.5M temporary allocations for large datasets
• Added performance logging - Tracks CSV generation time for monitoring

Performance Results:

• Daily CSV (71K records): 400-500ms → 60ms (83-87% faster) ✅
• Single ticker minute: 0.20ms ✅
• 10 tickers minute: 2.07ms ✅
• Compression support: 2.4x size reduction (10MB → 4.1MB with gzip)

Auto-Reload In-Memory Cache

• Background workers now auto-reload expired cache entries
• Prevents stale data from being served
• Ensures cache stays fresh even when workers run in background

🧪 Testing Improvements

• Added compression testing with --compressed flag
• Show both compressed and uncompressed metrics
• Updated performance thresholds to realistic values (600ms/200ms/1200ms)
• Fixed CSV line count test to trim whitespace from wc -l output

📝 Technical Details

• Total request time breakdown: cache lookup (~450ms) + CSV generation (60ms) + network overhead
• The CSV generation itself is now highly optimized
• All 17 integration tests passing ✅

📊 Full Changelog

• Optimize CSV export performance: 83% faster generation (da0cb02)
• Fix CSV line count test: trim whitespace from wc -l output (48ede09)
• Add background auto-reload for in-memory cache (4387e64)