Function hash_strict 

pub fn hash_strict(bytes: &[u8]) -> HashMatrix

This procedure implements the same hash function as hash(), but with a different performance tradeoff. The first time it’s invoked, hash computes a 4MiB table of all the hashes for every pair of bytes, which are then used to double hashing speed. For applications that need to do a lot of hashing, this is nearly twice as fast as hash(), but it also requires much more memory and initialization time. As a rule of thumb, if you’re going to hash less than 100KiB during your program’s execution, you should probably use hash_strict.