OpenELEC uses very little system resources for processor or memory. There’s no need to use any special customization tips to get good performance with the RPi2. There’s also no need to overclock the machine, reduce the resolution of videos, or use a different skin (although I really like the Amber skin). Using the RPi2 as a media centre has a downside. That’s you miss out on all the other wonderful and weird ways to use the wee machine. But that’s easily solved; just buy another RPi2, they are so inexpensive. Or better yet, buy a RPi2 for each room.