澄清：这个问题与加工速度无关;关于让它变得更快的答案是无关紧要的.

foreach (int i=0; i<some_big_number; i++)
{
    using (myDC dc = new myDC())  // my DataContext
    {
        myRecord record = (from r in dc.myTable where r.Code == i select r).Single();

        // do some LINQ queries using varIoUs tables from the data context
        // and the fields from this 'record'.  i carefully avoid referencing
        // any other data context than 'dc' in here because I want any cached
        // records to get disposed of when 'dc' gets disposed at the end of 
        // each iteration.

        record.someField = newValueJustCalculatedAbove;
        dc.SubmitChanges();
    }
}