Entity Framework Core Articles

Need only active customers?

Filter them in the database.

Instead of:

var customers = await context.Customers.ToListAsync();

var activeCustomers = customers
    .Where(x => x.IsActive)
    .ToList();

Prefer:

var activeCustomers = await context.Customers
    .Where(x => x.IsActive)
    .ToListAsync();

The difference is where filtering happens.

The first approach:

• Loads every row
• Transfers every row
• Stores every row in memory
• Filters afterward

The second approach lets the database return the rows you requested.

If you need 100 customers from a table containing 1,000,000 rows, filtering before ToListAsync() tends to matter.

Reading data that you don't plan to update?

Consider AsNoTracking().

var products = await context.Products
    .AsNoTracking()
    .Where(x => x.IsActive)
    .ToListAsync();

By default, EF Core tracks entities so it can detect changes and persist them later.

For read-only scenarios, that tracking work might not be needed.

AsNoTracking() helps by:

• Avoiding change tracking
• Reducing tracking-related memory usage
• Making the intent of the query explicit
• Working well for API reads and reporting
• Keeping read-only queries focused on reading

If you don't plan to change the entity, consider asking EF Core not to track changes.

Need to run logic for every incoming HTTP request?

Use ASP.NET Core middleware.

Common middleware scenarios:

• Logging requests
• Handling exceptions
• Authentication
• Authorization
• Adding custom headers
• Response compression

Middleware executes in the order you register it in the pipeline.

Each middleware can inspect the request, perform work, and pass execution to the next middleware.

Want asynchronous database writes in EF Core?

Use SaveChangesAsync() instead of SaveChanges().

Benefits:

• Doesn't block the calling thread
• Works better under load
• Integrates with async/await
• Recommended for ASP.NET Core applications
• Available since EF Core was released

What other EF Core performance tips do you use?