Hardware vs software

DES is kind of optimised for doing it in hardware, so don't take how slow it is in software as the limit for good encryption.

I wasn't saying that DES was the fastest of all possible secure ciphers. I was saying that DES is the fastest of all ciphers which are widely believed to be secure. This aspect of security is moderated by the key length of DES, which is too short to be secure against a well-funded opponent at present, but which is perfectly adequate for other purposes. Eric