Linq的执行效率及优化

List<int> source = new List<int>();
var rand = new Random();
int i = 5000;
while (i > 0)
{
    i--;
    source.Add(rand.Next(1, 500));
}

Stopwatch watch = new Stopwatch();

watch.Restart();
var temp2 = from s in source orderby s where s > 100 select s;
int count2 = temp2.Count();
watch.Stop();
Console.WriteLine("orderby s where s > 100: " + watch.ElapsedTicks);

watch.Restart();
var temp1 = from s in source where s > 100 orderby s select s;
int count = temp1.Count();
watch.Stop();
Console.WriteLine("where s > 100 orderby s: " + watch.ElapsedTicks);

1.FROM
2.WHERE
3.GROUP BY
4.HAVING
5.SELECT
6.DISTINCT
7.UNION
8.ORDER BY