To use Android effectively, you must root your device and freeze/remove unwanted apps. With root, you must also use a firewall to block or limit network access to you still want to use.
You must also mange your radios well - only enable Bluetooth and GPS when you need it, otherwise keep them off; toggle mobile data and wifi when you roam which means don't leave wifi on while you leave your residence or workplace, and don't leave either on at night or for extended time. (Yes there is a lag in the morning when you turn on wifi and all the background apps sync at once to get email, messages, updates, etc. but you trade that for longer battery life by not using as many charge cycles.)
Managing both software and hardware is a bitch, but if you spend a bit of time to learn, you can get great battery life and overall performance (less background apps), and enjoy enhanced privacy (block ads, prevent data leaks, don't respond to wifi/BT pings, etc).
Why bother having a smart phone if you're going to do all of that?
The trouble with being poor is that it takes up all your time.