Thanks for your contribution! I'm thinking of just making nacl-fast.js the default ("main"), and those who need the original version can just require('tweetnacl/nacl.js') (that's what I currently do for the fast version in one of my projects). What do you think?

Sure, that would be great. In my tests, EdDSA is much faster with the -fast library. Thanks for tweetnacl-js!