The K6 series actually had the best branch prediction of any x86 processor. I believe that the Mustang core will be as good as the K6 series was. (Around 95 or 96 percent I believe) According to memory, the Athlon is at about 91 percent. I pulled these numbers out of my head, but I believe they are right. The pipeline will be increased by 2 stages I believe, unfortunately I don't have time to look it up🙁 With the better brance prediction, and rumored cache enhancements--lower latency, and 256 bit bus to the L2--these will more than offset the longer pipe. So, clock for clock the Mustang core should be faster, and it will be able to ramp much higher. Ace's Hardware has some very good reads on this and the P4.