This app was mentioned in 6 comments, with an average of 2.50 upvotes
i do the same as you. another great tool is with trepn you can figure out what apps are doing in the background. it logs all data activity over cell and wifi networks. you can easily spot an app logging data and sending it off in the background. with lollipop's bug of apps keeping mobile radio active it's super helpful.
Check this app: https://play.google.com/store/apps/details?id=com.quicinc.trepn
Start a CPU profiler for a few minutes and look what apps hog your cpu.
Also, you can turn on stamina with CPU underclock option turned on.