I recently updated from Mavericks to Yosemite on my 2012 rMBP. Even with no transparency on my battery life was down from 6+ hours to less than 3.5 hours! And everything is so annoyingly slow. After 3 days with Yosemite I had to use my wife's 2009 Air for something, it's running Mavericks, and wow, the speed! That day I restored from a backup and now I am back to running 10.9. My battery is back to 6+ hours, and my l…
Actually your memory usage should go down with Yosemite -- they have new technologies just for that. Same for battery file, it should go up.
Since this is HN, do people do basic investigation, or assume that anything that doesn't seem to work is a lost cause and just switch OSs, re-install, or complain?
Your experience for example seems more like some rogue app with extensive CPU/memory usage driving the battery down. Have you checked Activity Monitor to try to spot if that was the case?