Phone Lags after root and Greenify Problem topic

I just rooted my N910C and i noticed it lags? i try to install Greenify and also it lags sometimes it wont even ask for SuperSU access and i tried turning off the power saving and even if its off the icon on status bar is still there. another thing is that when i install greenify i can't un install it normally i tried on google store and the only option is Deactivate. i tried uninstalling it via "Drag icon and drag to the trash can icon" and it says that i need to disable the administrator access and i tried unchecking it but it lags. so what i did was uninstall it via titanium back up and it worked. but still my phone lags any suggestion?