Article: http://www.zzzprojects.com/entity-framework/how/performance-insert

entity-framework-how-performance-insert-example-1.cs

using (var ctx = new CustomerContext())
{
    List<Customer> customers = new List<Customer>();
    
    foreach(var line in lines)
    {
        var customer = new Customer();
        // ...code...
        
        customers.Add(customer);
    }
    
    ctx.Customers.AddRange(customers);

    ctx.SaveChanges();
}

entity-framework-how-performance-insert-example-2.cs

using (var ctx = new CustomerContext())
{
    // 1. CREATE a list
    List<Customer> customers = new List<Customer>();
    
    foreach(var line in lines)
    {
        var customer = new Customer();
        // ...code...
        
        // 2. ADD entity to the list
        customers.Add(customer);
    }
    
    // 3. USE BulkInsert
    ctx.BulkInsert();
    
    // 4. Done!
}