Preformance Issue with Linq to SQL

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C#

LINQ

Why is there such a big preformance Issue when using .Where method with DataContext?

Example 1, takes under 1sec to retrieve it's values.

public List<EMPLOYEE> FindEmployees(string prefix)
        {
            var query = (from e in context.EMPLOYEEs
                        where e.EMP_SURNAME.ToUpper().StartsWith(prefix)
                        orderby e.EMP_SURNAME
                        select e).Take(15);

            return query.ToList();
        }

Example 2. Takes up to 10sec

public List<EMPLOYEE> FindEmployees(Func<EMPLOYEE, bool> predicate, int count)
        {
            var query = context.EMPLOYEEs.Where(predicate).Take(count);
            return query.ToList();
        }

And I would call this methods like this.

var employees = FindEmployees(p => p.EMP_SURNAME.ToUpper().StartsWith(prefixText.ToUpper()), 15);

Please any help would be much appreciated.