> 90 MHz Pentium 200 MHz DEC Alpha > DES Encrypt 8.0 MegaBits/Sec 10.6 MegaBits/Sec > RC5 Encrypt 26.3 MegaBits/Sec 24.5 MegaBits/Sec I think best DES speed is closer to 18 MBits/Sec on a 200 MHz Alpha; I'd imagine the RC5 time cannot be improved, so a 2/3 ratio is realistic for that machine.