We're seeing strange behavior when running two versions of a query on SQL Server 2005:

version A:

SELECT otherattributes.* FROM listcontacts JOIN otherattributes
ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = 1234
ORDER BY name ASC

version B:

DECLARE @Id AS INT;
SET @Id = 1234;
SELECT otherattributes.* FROM listcontacts JOIN otherattributes
ON listcontacts.contactId = otherattributes.contactId  
WHERE listcontacts.listid = @Id
ORDER BY name ASC

Both queries return 1000 rows; version A takes on average 15s; version B on average takes 4s. Could anyone help us understand the difference in execution times of these two versions of SQL?

If we invoke this query via named parameters using NHibernate, we see the following query via SQL Server profiler:

EXEC sp_executesql  N'SELECT otherattributes.* FROM listcontacts JOIN otherattributes ON listcontacts.contactId = otherattributes.contactId WHERE listcontacts.listid = @id ORDER BY name ASC',
     N'@id INT',
     @id=1234;

...and this tends to perform as badly as version A.