How To Design A Thorough Test Plan?

I am going to handle a test to a list of querys to find their efficency(spending of time)

here is my test plan:

there are query A¡¢B¡¢C..., and insert all querys into a table called querytbl;
open a cursor for all records from querytbl;
fetch next query from cursor;
while @@fetchstatus = 0
begin
exec query for 3 times and calculate average spending of time;
fetch next query from cursor;
end
...

Is there any better test plan?(just test spending of time)
or test tools?