Optimize React rendering and data processing performance

[Copilot]

Performance bottlenecks identified: redundant re-renders, O(n*m) cart lookups, 7+ filter passes through sales data, and duplicate utility functions.

React Component Optimizations

• ProductCard/ProductGrid: Wrapped with React.memo() to prevent unnecessary re-renders
• Cart lookups: Replaced cart.some(item => item.id === product.id) with Set.has() for O(1) lookups

  // Before: O(n*m) - checks array for every product on every render
  isInCart={cart.some(item => item.id === product.id)}
  
  // After: O(n) setup + O(1) lookups
  const cartItemIds = useMemo(() => new Set(cart.map(item => item.id)), [cart]);
  isInCart={cartItemIds.has(product.id)}

Reports Page - Single-Pass Processing

Replaced 7+ separate filter operations with single-pass aggregation:

// Before: O(7n) - multiple passes through sales array
const todaysSales = sales?.filter(sale => isToday(...)).reduce(...)
const weeklySales = sales?.filter(sale => isThisWeek(...)).reduce(...)
// ... 5 more filters

// After: O(n) - one pass, all metrics
sales.forEach(sale => {
  const revenue = sale.price * sale.quantity;
  totalRevenue += revenue;
  if (dateHelpers.isToday(saleDate)) todaysSales += revenue;
  if (dateHelpers.isThisWeek(saleDate)) weeklySales += revenue;
  // ... all calculations in single pass
});

Memoized all derived calculations (salesMetrics, debtMetrics, inventoryValue, reportsData).

Hook Optimizations

• useCart: Memoized totalPrice and totalItems calculations
• useProductSearch: Memoized filteredProducts computation

Service Layer

• inventoryService: Added initialization flag to prevent redundant localStorage parsing on every access

Code Quality

• Consolidated duplicate formatPrice function from 3 locations into shared utility at src/utils/formatPrice.ts

See PERFORMANCE_IMPROVEMENTS.md for detailed analysis.

Original prompt

Identify and suggest improvements to slow or inefficient code

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Project	Deployment	Preview	Comments	Updated (UTC)
benta-ko	Ready	Preview	Comment	Dec 8, 2025 5:31am