Cryptographic hash functions can be orders of magnitude slower than functions tuned for hashtables and dictionaries. If you’re using them as hash table indexes,

Cryptographic hash functions can be orders of magnitude slower than functions tuned for hashtables and dictionaries. If you’re using them as hash table indexes, then you have to take the big cryptographically secure number and mod it by a small bucket count - and then you’re going to have collisions. If you don’t salt, then an attacker is going to predict the bucket indexes no matter how strong your hash function is, and since you can’t have that many buckets, they can just brute force to find collisions. Salting is the way to deal with these issues, and for hash tables it works well even if your hash function isn’t cryptographically secure. Hence, for hash tables, salt+fast hash function should be sufficient.