Consider if a 16-bit salt is used, and it is uniformly applied over a very large password file (200,000 entries). An attacker wants to see if one particular password (say, "bubba") is used by any of the password entries. How many encryptions must be calculated, and how many comparisons must be made (of their generated-hash vs. stored hash values)?
Assume the attacker has the stored-hash-values, but he does not know which salt is used for any individual password hash. In other words, they can see
/etc/passwd (so they know the 200,000 usernames), and have only gained access to the hash (but not the salt-portion) of what is stored in