I recently purchased a Lenovo ThinkPad T430u, and installed Xubuntu. I've noticed it has poor battery life.
How can I optimize the battery life? Is this a problem with the desktop environment, or Linux itself?
This question could easily be phrased "How can I increase the battery life on my laptop which runs Linux", and there are a plethora of answers, tips and tricks on the Internet - a fair amount of which involve installing powertop, seeing what is consuming the power and tweeking it.
From what I have researched, I highly doubt that Xubuntu drains the battery more then other Windows managers, so to that extent, you could blame Linux itself, although that is unfair, as its the configuration rather then the OS.
(Some ways you can reduce battery life include spinning down your disks when not in use, reducing brightness of the screen when on battery, ensuring your computer uses an "On-Demand" governor to ensure the speed of the CPU is kept low when idle, fan management, interupt management, making hard drive writes more efficient by enabling caching if you are willing to rely on your battery to ensure your hard drive always gets the power it needs - even in event of a sudden power outage, removing some programs which are CPU guzzlers etc.)