my specs are not comparable to you (mine is potato) but i think the game being laggy is the client's fault so nothing can be done there.. as for the CPU i'm not sure about that but i use a program called cleanmem whih automatically or manually closes unnecessary programs to give more memory (it does not close the one your using - look it up because they give more detailed explanation what it does) in the process of that it also free up the CPU usage

Edit: i also noticed that u mentioned using multiple accounts during Sage Battlefield, i hope u don't use it to benefit ur main acc (killing ur alt over and over again) because u can get banned "i think".. if that is the case u dug ur own grave by posting this on forum