How can I convert my linq to SQL old school Query for better performance?

Hi; I want to improve my query performance , When you take a look for my previous question, you will see ny question . I asked to  you for modifying of my linq query.Because I need really better performance .

But I decided to look at the equality of SQL for my linq query. As a result, How can I convert below linq to SQL  with taking care of performance issue? Because I need to have a better performance that's the reason;  it is more essential than before.A guy who is willing to answer this question   has to focus on

1) better performance
2) sql equality.

   string sortColumnName = GetSortColumnName(request);

            if (!string.IsNullOrEmpty(sortColumnName))
            {
                queryOrdered = queryOrdered.OrderBy(sortColumnName);
            }

            var data = await queryOrdered.Skip(request.Start).Take(request.Length).ToListAsync().ConfigureAwait(false);

            data.ForEach(x =>
            {
                foreach (var item in x.SalesItems)
                {
                    if (flightSalesItemType.Any(y => y == item.Value))
                    {
                        var flightSales = DbContext.Set<FlightTicketNumber>().Include(q => q.FlightPassenger).Include(q => q.FlightTicketFare).FirstOrDefault(q => q.SalesItemId == item.Key);
                        if (flightSales != null)
                        {
                            var flightLeg = DbContext.Set<FlightLeg>().Include(q => q.Airline).FirstOrDefault(q => q.PNRId == flightSales.PNRID);

                            x.TicketNo = flightSales.TicketNumber;
                            x.ServiceFee = flightSales.FlightTicketFare.Sum(t => t.ServiceFee);
                            x.PassengerName = flightSales.FlightPassenger.Name + " " + flightSales.FlightPassenger.Surname;
                            x.AirlineProviderName = flightLeg.Airline.Code;
                            x.Route = flightLeg.OriginCityCode + " - " + flightLeg.DestinationCityCode;
                        }
                    }
                }
            });

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