Optimization - sql :How to show all data exists in multiple tables

I have two table. I want to find all the rows in table One that exists in table Two, and back. I had the answer, but I want it faster. Example:

Create table One (ID INT, Value INT, location VARCHAR(10))
Create table Two (ID INT, Value INT, location VARCHAR(10))

INSERT INTO One VALUES(1,2,'Hanoi')
INSERT INTO One VALUES(2,1,'Hanoi')
INSERT INTO One VALUES(1,4,'Hanoi')
INSERT INTO One VALUES(3,5,'Hanoi')

INSERT INTO Two VALUES(1,5,'Saigon')
INSERT INTO Two VALUES(4,6,'Saigon')
INSERT INTO Two VALUES(5,7,'Saigon')
INSERT INTO Two VALUES(2,8,'Saigon')
INSERT INTO Two VALUES(2,8,'Saigon')

And answers:

SELECT * FROM One WHERE ID IN (SELECT ID FROM Two)
UNION ALL
SELECT *FROM Two WHERE ID IN (SELECT ID FROM One)

If I have big data, it will be very slow. How can I rewrite this query to run quickly?