People like me like to look at what’s happening on their computer via Activity Monitor, which you’ll find in the Utilities folder within the Applications list. It shows the programs running at any given moment, including background tasks, and what CPU/memory resources they’re taking up.
A few days ago while at a cafe I spotted something called VTDecoderXPCService was chewing-up about 10-15% of my MacBook Pro’s CPU’s power. CPU usage eats battery life, so I was anxious to find what this mysterious app was. A quick Googling revealed it was something to do with video playback* but I had no media playback apps open.
Hmmm… Then I found the answer. I had System Preferences open, and in particular the Trackpad component. This shows demonstration movies of how a trackpad can be used… And it uses VTDecoderXPCService to do so.
Even if it’s minimized, System Preferences still uses VTDecoderXPCService, with the same consumption of CPU power. The solution is simple: Quit System Preferences, but also keep it closed if you’re using a MacBook on battery power. (Strangely, it seems System Preferences doesn’t automatically terminate, like some other apps do in Mountain Lion; with the above in mind, System Preferences is actually a great candidate to go away should the user forget about it.)
* Specifically, VTDecoderXPCService is a sandboxed system component for playing videos.