⚡ How to Optimize EF Core Queries for Better Performance

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Published on: June 6, 2025

Category: Performance Tuning

Tags: Entity Framework Core, EF Core Performance, .NET Optimization, Query Tuning, LINQ, Database Best Practices

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🚨 Common EF Core Pitfalls

Before jumping into optimizations, let’s identify common mistakes:

• Overusing .Include() for relationships that aren't needed
• Fetching more data than necessary (wide SELECTs)
• Not using .AsNoTracking() for read-only queries
• Making multiple small queries instead of batching

✅ 1. Use .AsNoTracking() When You Don’t Need to Track

var users = await context.Users
    .AsNoTracking()
    .Where(u => u.IsActive)
    .ToListAsync();

✅ This can improve read performance by up to 50% in large datasets because EF skips change tracking.

✅ 2. Avoid N+1 Problems with Proper .Include()

// Good: eager load related data when needed
var orders = await context.Orders
    .Include(o => o.Customer)
    .Include(o => o.Items)
    .ToListAsync();

🧠 Only include what you need. Too many .Include()s can bloat query size and response time.

✅ 3. Use Projection Instead of Loading Entire Entities

var summaries = await context.Orders
    .Where(o => o.OrderDate > DateTime.UtcNow.AddDays(-30))
    .Select(o => new {
        o.Id,
        o.Total,
        o.Status
    })
    .ToListAsync();

✅ Load only the columns you need — this reduces memory use and speeds up serialization.

✅ 4. Filter Early, Not Late

// Good
var filtered = await context.Products
    .Where(p => p.IsAvailable && p.Price < 100)
    .ToListAsync();

⛔ Avoid applying filters in memory after .ToList(). Always push filters to the database.

✅ 5. Use Compiled Queries (Advanced Use)

static readonly Func<AppDbContext, int, Task<User?>> GetUserById =
    EF.CompileAsyncQuery((AppDbContext ctx, int id) =>
        ctx.Users.FirstOrDefault(u => u.Id == id));

🧠 Bonus Tips

• Index columns used in filters and joins
• Monitor SQL logs via ToQueryString() or ILogger
• Use FirstOrDefaultAsync or AnyAsync instead of Count() when checking existence
• Avoid loading child collections if you're not using them

📊 Tools to Monitor EF Core Performance

• EF Profiler
• MiniProfiler
• SQL Server Query Store
• Application Insights (Azure)

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• 🔗 Blog: www.ajaygangwar.com
• 💼 LinkedIn: Ajay Gangwar
• 📧 Email: seajaygangwar@gmail.com

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