Question

I am having performance issues with this LINQ Query.
The data is laoded into to this.students already.
Now when I call the GetStudentData function say 1000 times it has a huge overhead.
Is there a way of improving this without changing the LINQ to a loop

   public Student GetStudentData()
   {         
          IEnumerable<Students> studentTypes = this.students.Where(x => (x.studentsId  == studentId && x.StduentType.Equals(studentType)));
          if(studentTypes.Count==0) return new Student() { studentid=studentID};
          return (Student)studentTypes.First();
   }

So here are the results when looping through it 10000 times with my original version

Original Version : 5.6 seconds on the average
New Version @des’s Code with FirstOrDefault : 3.6 seconds

Answer 1

When you use Where you loop through all records which fulfill given conditions, when you use First you just search for first record which fullfills condition, so using First should speed it up.

public Student GetStudentData()
{         
    // get first student by id and type, return null if there is no such student
    var student = students.FirstOrDefault(i => i.studentsId == studentId && i.StudentType.Equals(studentType));

    // if student is null then return new student
    return student ?? new Student();
}