One of the most important aspect of performance for Windows 7 is energy efficiency. With the new operating system, Microsoft is introducing technology aimed at reducing the computer's energy consumption and boosting laptop battery life. For instance, in a procedure that the company calls timer coalescing, Windows 7 will simultaneously perform certain routine tasks that require the processor, which in turn allows the computer to spend more time in lower-power mode.
Battery-life tests were a wash. While one of our PCs gained 15 minutes of run time with Windows 7, the other improved by 1 minute. Your mileage may vary. *Times are in hours:minutes. Longer times indicate better performance.>In our tests, the Gateway T-6815 laptop gained an additional 15 minutes of battery life on average with Windows 7. Running under Vista, the Gateway lasted 2 hours, 58 minutes on a single battery charge; under Windows 7 it ran for 3 hours, 12 minutes. Our Lenovo Y530, in contrast, eked out an insignificant 1-minute improvement with Windows 7.
Of course, your individual system-performance gain will depend to a large extent on your setup, but our results were still encouraging. At best, your laptop will gain a few extra minutes of run time; at worst, the battery life will be about the same as it was under Windows Vista.
none can deny the fact that windows 7 gain battery life