Which Techniques Work Best for Optimizing the Performance of EF Core?

Overview of EF Core Performance Enhancement
Although Entity Framework Core (EF Core) is a strong and adaptable ORM for.NET, improper use might result in performance snags. With real-world C# examples, we'll examine recommended practices for enhancing EF Core performance, lowering query latency, and guaranteeing effective memory usage.

1. For read-only queries, utilize AsNoTracking()
When you're just reading data, EF Core doesn't need to track entities by default. Turning off tracking decreases memory use and speeds up queries.

var users = context.Users
    .AsNoTracking()
    .ToList();

When to Use

• In read-only queries
• In reporting or dashboard views
• When tracking adds unnecessary overhead

2. Project Only Required Columns with Select

Avoid fetching entire entities when you only need a few fields.

var names = context.Users
    .Select(u => u.Name)
    .ToList();

Benefits

• Reduces payload size
• Improves query performance
• Avoids unnecessary joins and data hydration

3. Avoid the N+1 Query Problem

The N+1 issue happens when lazy loading causes multiple queries unintentionally.

Bad

var orders = context.Orders.ToList();

foreach (var order in orders)
{
    Console.WriteLine(order.Customer.Name); // Triggers a query each time
}

Good (Eager Loading)

var orders = context.Orders
    .Include(o => o.Customer)
    .ToList();

4. Use Batching with AddRange / UpdateRange

Instead of calling SaveChanges() repeatedly, batch your inserts or updates:

context.Users.AddRange(user1, user2, user3);
await context.SaveChangesAsync();

For large batches

Use libraries like EFCore.BulkExtensions to dramatically reduce insert/update time.

5. Prefer FirstOrDefault() or Any() Instead of Count()

Count() checks all matching rows. Use Any() if you just need to check existence.

// Slower
bool hasUsers = context.Users.Count() > 0;

// Faster
bool hasUsers = context.Users.Any();

6. Use Indexes on Frequently Queried Columns

EF Core doesn’t manage database indexes, you must define them manually or in your migrations:

modelBuilder.Entity<User>()
    .HasIndex(u => u.Email)
    .IsUnique();

When to Use

• On columns used in WHERE, JOIN, or ORDER BY
• For foreign keys or commonly filtered fields

7. Use ToList() or ToArray() at the Right Time

Don’t call ToList() too early if you can keep the query in-memory longer to add more filters or projections.

example:

var recentUsers = context.Users
    .Where(u => u.CreatedAt > DateTime.UtcNow.AddDays(-7))
    .Select(u => u.Name)
    .ToList(); // Only at the end!

8. Use Compiled Queries for High-Throughput Scenarios

Compiled queries cache the query translation step, reducing overhead on repeated execution.

private static readonly Func<AppDbContext, int, User?> _getUserById =
    EF.CompileQuery((AppDbContext context, int id) =>
        context.Users.FirstOrDefault(u => u.Id == id));

// Usage
var user = _getUserById(context, 5);

9. Cache Frequently Used Data
Don’t hit the database for static data. Use in-memory caching:

var roles = memoryCache.GetOrCreate("roles", entry =>
{
    entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromHours(1);
    return context.Roles.AsNoTracking().ToList();
});

Or use a distributed cache for multiple server environments.

10. Use async Queries for Scalability

Always prefer async versions of EF Core methods:

var user = await context.Users
    .FirstOrDefaultAsync(u => u.Email == "[email protected]");

Benefits

• Prevents thread blocking
• Improves scalability in web apps

11. Avoid Unnecessary Change Tracking and Detach When Needed

If you need to load and discard data without tracking:

context.Entry(entity).State = EntityState.Detached;

Useful in long-running contexts or background jobs to avoid memory bloat.

12. Profile Queries and Use Logging

Use tools like:

• EF Core logging (ILogger)
• MiniProfiler
• SQL Server Profiler
• Visual Studio Diagnostic Tools

To inspect:

• Query duration
• Redundant database calls
• Unoptimized SQL generated by LINQ

13. Use Raw SQL for Complex Queries (When Necessary)

When LINQ becomes inefficient or unreadable:

var users = context.Users
    .FromSqlRaw("SELECT * FROM Users WHERE IsActive = 1")
    .AsNoTracking()
    .ToList();

Be cautious with SQL injection, parameterize your queries!

14. Use Route-Level Filtering in APIs

Instead of filtering in-memory or in the controller, do it in the query itself:

// Good
var result = await context.Users
    .Where(u => u.Role == "Admin")
    .ToListAsync();

Conclusion

EF Core is powerful, but performance can suffer without thoughtful design. Apply these best practices to:

• Reduce latency
• Minimize memory usage
• Avoid costly database operations
• Scale efficiently

A fast app is a happy app, optimize early, monitor often!

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