16. Performance Requirements

16.1 Performance Benchmarks

Core Operations

File Processing

Database Operations

UI Responsiveness

16.2 Resource Usage Limits

Memory Constraints

CPU Usage

Network (Local API Calls)

16.3 Optimization Strategies

Backend Optimizations

-- Performance-critical indexes
CREATE INDEX idx_currency ON calculations(currency);
CREATE INDEX idx_timestamp ON calculations(timestamp DESC);
CREATE INDEX idx_currency_timestamp ON calculations(currency, timestamp DESC);

from decimal import Decimal, getcontext

# Set precision for financial calculations
getcontext().prec = 28  # 28 decimal places

# Always use Decimal for money
amount = Decimal("1850.50")  # ? Correct
# amount = 1850.50  # ? Avoid floats for money

# Bulk insert optimization
with db.begin():
    for calc in calculations:
        db.add(Calculation(**calc))
    # Commits once at the end (faster than individual commits)

Frontend Optimizations

// Use React.memo for expensive components
const BreakdownTable = React.memo(({ breakdown }) => {
    // Component only re-renders if breakdown changes
});

// Debounce user input
const debouncedAmount = useDebounce(amount, 300);

// Code splitting for routes
const HistoryPage = lazy(() => import('./pages/HistoryPage'));
const BulkUploadPage = lazy(() => import('./pages/BulkUploadPage'));

import { FixedSizeList } from 'react-window';

// Render only visible items for 1000+ row tables

  {Row}

16.4 Scalability Considerations

Current Limits (Phase 1)

Future Scalability (Phase 2+)

• Cloud Sync: PostgreSQL backend for multi-device sync
• Multi-User: Authentication + user isolation
• API Rate Limiting: Prevent abuse in public API
• Horizontal Scaling: Load balancer + multiple backend instances
• CDN: Static asset delivery for web version
• Caching Layer: Redis for frequently accessed data

16.5 Performance Monitoring

Backend Logging

import logging
import time

logger = logging.getLogger(__name__)

# Performance logging decorator
def log_performance(func):
    def wrapper(*args, **kwargs):
        start = time.perf_counter()
        result = func(*args, **kwargs)
        duration = time.perf_counter() - start
        
        logger.info(f"{func.__name__} completed in {duration*1000:.2f}ms")
        
        if duration > 1.0:  # Warn if > 1s
            logger.warning(f"Slow operation: {func.__name__} took {duration:.2f}s")
        
        return result
    return wrapper

@log_performance
def process_bulk_upload(file):
    # Function implementation
    pass

Frontend Performance Monitoring

// React component render tracking
useEffect(() => {
  console.time('CalculatorPage render');
  return () => {
    console.timeEnd('CalculatorPage render');
  };
}, []);

// API call timing
const fetchData = async () => {
  const start = performance.now();
  const response = await axios.get('/api/v1/history');
  const duration = performance.now() - start;
  
  console.log(`API call took ${duration.toFixed(2)}ms`);
  return response.data;
};

Health Check Script

File: health-check.ps1

Write-Host "=== System Health Check ===" -ForegroundColor Cyan

# Check backend
$backendUrl = "http://localhost:8000/health"
try {
    $response = Invoke-RestMethod -Uri $backendUrl -TimeoutSec 5
    Write-Host "? Backend: HEALTHY" -ForegroundColor Green
    Write-Host "  Database: $($response.database)"
    Write-Host "  Version: $($response.version)"
} catch {
    Write-Host "? Backend: OFFLINE" -ForegroundColor Red
}

# Check database size
$dbPath = "currency_calculator.db"
if (Test-Path $dbPath) {
    $dbSize = (Get-Item $dbPath).Length / 1MB
    Write-Host "? Database: $($dbSize.ToString('F2')) MB" -ForegroundColor Green
    
    if ($dbSize > 50) {
        Write-Host "  WARNING: Database > 50MB (consider cleanup)" -ForegroundColor Yellow
    }
}

# Check Tesseract
try {
    $tesseractVersion = & tesseract --version 2>&1 | Select-Object -First 1
    Write-Host "? Tesseract: $tesseractVersion" -ForegroundColor Green
} catch {
    Write-Host "? Tesseract: NOT FOUND" -ForegroundColor Red
}

# Check Poppler
try {
    $popplerVersion = & pdftoppm -v 2>&1 | Select-Object -First 1
    Write-Host "? Poppler: $popplerVersion" -ForegroundColor Green
} catch {
    Write-Host "? Poppler: NOT FOUND" -ForegroundColor Red
}