No, you can have like 20k lines of code, but if you don't use it, it will NOT use any memory. MAYBE a tiny bit. However it will take forever to compile
Methods only use your memory if they are being processed...
EDIT:
Classes MIGHT take up space if you made an instance for them, the 'super' class has to like loop through the class or something. If you're not using a class file, don't make an instance for it...