Time Machine makes it very easy to back up all the data on your Mac, but copying that data to another drive consumes system resources. Fortunately, you can turn off Time Machine while your laptop is running on battery power.
Believe it or not, private browsing will let you squeeze out a bit more battery life, because the browser is no longer accessing the hard drive to cache pages and images. Of course, Safari won’t remember your search history or autofill forms, so you have to balance its convenience with the potential battery savings.
Apple’s Spotlight, which instantly returns search results of everything on your hard drive, is very useful. But the way it works consumes CPU resources. You can prevent Spotlight from searching your drive.
MacBook Pros have both integrated and discrete GPUs and can switch between the two seamlessly, so you can get better battery life or increased performance, depending on the task. However, the discrete GPU can seriously cut into battery life.
Even when not in use, whenever you have an optical disk in your notebook, the system will occasionally spin up the drive (and the laser) to check the disk. While this isn’t an issue for MacBook Airs, which lack optical drives, you can save battery life by disconnecting any peripherals, such as external hard drives and mice. These devices don’t draw a ton of power, but every little bit helps.