It should be noted that while the actual execution time doesn't take any longer (compared to the Athlon), it *does* take up more cache to store a 64-bit data type vs a 32-bit data type and also takes more memory bandwidth to transfer it. So all those extra zero's will eat up cache space and memory bandwidth. Luckily, AMD forsaw this and have set the default integer size on x86-64 to 32-bit. *However*, the memory pointer size (memory address) is 64-bit in all 64-bit modes (including compatibility) unless specifically told otherwise, so memory addresses will take up extra cache space and memory bandwidth.