Yeah SHA3 isn't directly for password hashing. You should use a memory strong PBKDF (password based key derivation function) like Argon2, bcrypt, or scrypt. These functions are all constructions that run the hash many times, so the underlying hash speed is irrelevant

For high entropy inputs, like for a HMAC signature, you want the hash to be fast because its practically impossible to brute force the 256bit input key, and you often apply this to large inputs.