sql server 查询中IN和OR的速度比较？？

1、USE pubs

SELECT au_lname, state
FROM authors
WHERE state = 'CA' OR state = 'IN' OR state = 'MD'
------------------------------------------------------------------------------------
2、USE pubs

SELECT au_lname, state
FROM authors
WHERE state IN ('CA', 'IN', 'MD')
-------------------------------------------------------------------------------------
上面两条查询语句，同时查询一个有5万条数据的数据库，哪一个的查询速度快？？？？？？？？？？
为什么？？？？？？？why???why????why????

急待解答!!!!!!!!!!