SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED


Turn off ObjectTrackingEnabled  Property of Data Context If Not Necessary
using (NorthwindDataContext context = new NorthwindDataContext())
{
  context.ObjectTrackingEnabled = false;
}


  1. Do NOT Dump All Your DB Objects into One Single Data Context
  2. Use Compiled Query  Wherever Needed
  3. Filter Data Down to What You Need Using DataLoadOptions.AssociateWith
  4. Turn Optimistic Concurrency Off Unless You Need It
  5. Constantly Monitor Queries Generated by the Data Context and Analyze the Data You Retrieve
  6. Avoid Unnecessary Attaches to Tables in the Context
  7. Be Careful of Entity Identity Management Overhead 
  8. Retrieve Only the Number of Records You Need
  9. Do not  Misuse Compiled Query
public static Func<Northwnd, string, IQueryable<Customer>>
    CustomersByCity =
        CompiledQuery.Compile((Northwnd db, string city) =>
            from c in db.Customers where c.City == city select c);

public static Func<Northwnd, string, IQueryable<Customer>>
    CustomersById = CompiledQuery.Compile((Northwnd db,
    string id) => db.Customers.Where(c => c.CustomerID == id));

public IEnumerable<Customer> GetCustomersByCity(string city)
{
    var myDb = GetNorthwind();
    return Queries.CustomersByCity(myDb, city);
}
 
Reference:http://msdn.microsoft.com/en-us/library/system.data.linq.compiledquery.aspx