Remember, the #1 rule of new instruction sets released by Intel (at least in the past ~5 years) is that they are always close to useless in the first architectu

Remember, the #1 rule of new instruction sets released by Intel (at least in the past ~5 years) is that they are always close to useless in the first architecture that supports them. For example, PHADDW took 6 cycles on the Core 2 Conroe, making it almost useless in real code. But the Penryn doubled its speed, making it potentially useful. The string operations are, last I saw, something on the order of 9 cycles latency, making them rather unfortunately slow in practice... fitting perfectly with the trend mentioned above.