if you're using p51xx series tab and running cm 12.1 there are many users who face this problem, even I did with android andi cm12.1 at certain build, but there are also others who didn't faced such problem. while some works for few, some won't work for others. the best advice from me is, you got to try all the ROMs and see which one is stable for you. candy5 worked for, even blisspop did not rebooted in my case, for others it wasn't worth anything those who couldn't find any stable version of lollipop for their tab have switched to KitKat version or stock. so you really gotta try your luck here. do a clean install, wipe data and check if it still reboots. if already on clean install, there is a little app called ram manager pro try that and keep running app limit to less amount in settings- developers.