Re: .....
I hope you're being sarcastic. On the off-chance that you're not, allow me to educate you a little about how CPUs work.
A CPU clocked at 2 Ghz (or any speed) will always use the same amount of power. Unused processing cycles go into something called the "Idle" process. A CPU can save power in one of two ways: shut off different components (like an integrated video component) or change the clock speed to reduce the voltage requirements.
Modern CPUs can change the clock speed (and hence the required voltage) on the fly--this is particularly important on laptops, where minimum CPU speeds might be 1GHz or less, and might go up to around 3Ghz.
So for live tiles, since disabling components is off the table (tiles don't require any secondary components to help), the question is: can the laptop manage updating tiles at the minimum clock speed/voltage requirement? The answer is yes, and easily. A computer will never (or at least rarely) increase its clock speed just to handle live tile updating.
The upshot is... the earth may be burned to a cinder, but Windows 8 won't have anything to do with it. In fact, given how much it shortens the extremely power-intensive boot and shut-down processes, it might put off that day a little.
Dan