It's absolutely nowhere near half for 32-bit systems. The main feature of 64-bit is to allow the addressing of more memory. There's the ability to handle more information at once because of an increased bus width, and also they handle smaller numbers more efficiently. There's also the ability to use some special 64-bit instructions. None of these features, however, make it twice as fast as the same CPU in 32-bit mode. Perhaps you didn't mean to phrase it to sound like that, I'm unsure. Handling more memory means the CPU has to work harder correct? It has the ability to handle more memory because the address bus is much wider, in 32-bit a smaller address bus is used. Bear in mind this memory only needs addressing if it exists, if you're using the same amount of RAM when you moved from 32-bit to 64-bit then it's not doing any more work, or at least nothing that would cause any kind of noticeable load or temperature increase.