Is there a better way to sort my IList-bound GridView?

Question

I have an asp.net web application that has a page with a GridView. The GridView is bound to an IList object. As you may know, the .net framework does not provide for sorting of such a GridView; the sorting must be handled in code.

Here's the code I was able to draft. As you can see, the issue is that the name of the field to sort by is given in the EventArgs as a string literal.

I need to get from knowing that EventArgs.SortExpression = "Subject" to telling the program to sort my list by task.Subject. If I understand correctly, this code is using the reflection libraries which are slow and should ordinarily not be used. Certainly, there is a faster way to do this. What would it be?

        protected void grvAllTasks_Sorting(object sender, GridViewSortEventArgs e)
    {
        get_data();
        IList<Task> tasks = (List<Task>) grvAllTasks.DataSource;


        if (e.SortDirection == SortDirection.Ascending)
        {                
            tasks = tasks.OrderBy( x =>
            {
                string propertyName = e.SortExpression;
                var propertyInfo = x.GetType().GetProperty(propertyName);
                var propertyValue = propertyInfo.GetValue(x, null);
                return propertyValue;
            }
        ).ToList();}
        else if (e.SortDirection == SortDirection.Descending)
            throw new NotImplementedException("sort descending not yet implemented");

        grvAllTasks.DataSource = tasks;
        grvAllTasks.DataBind();            
    }