It will. Unless you get a list of process and go in and manually disable each one you don't want then it will stay that way.
But remember if you don't know what you are disabling then don't do it, cause everything from WiFi not working, to the touchscreen not working can happen.
2 other items for you to ponder.... 1. don't mess with the developer setting unless you have to. 2. Install a antivirus if you don't have it already.
Also disabling items like auto rotation, face recognition, gyro and GPS and not using 4G unless you need to will help with that and your battery.
Games, email blah blah blah that alert you, push data etc will eat your RAM.
With about 50 of all things disabled on my phone that I never use, I still run about half RAM, its what Android does.