It takes 0.8ms the second time. 

The first time, it needs to create the hash table, and then it takes about 30ms.

Still, much better than 430ms.

Also, those 430ms are not invested. The second time will still take 430ms. So hashing on a very small bat is never a good investment. On the contrary, hashing on a larger (but not too much) table is a good investment. The next time a similar query comes in, it will be sub-millisecond.