Hashes are fast. To decide whether they are fast enough for your application the easiest, if not the only, way is to try it.

If once you've measured, you really need more speed, come back and ask again. Depending upon the nature of your keys there might be a faster mechanism, but be assured, it will involve considerably more work than using a hash. Once you know how fast the hash solution is, you'll be in a possition to decide if the extra work is worth the effort.