If Atom is so resource hungry, and I have alternatives which are not = IMHO the editor is a bad editor.
Use whatever you like, but it looks like the most important thing is that you like it, not that it's resource hungry.
> Not to mention that a 6MB file is pretty fucking big for something like atom.
This it the most funny part of your comment. I want my editor to open my files as they are. Some people could be happy with editors allowing for max. 20 lines per file, and I'm sure they would also claim that longer files are bad, so it's fine that an editor doesn't support that.
Use whatever you like, but don't claim that using 3GB of ram to open 6MB file is fine, because programmers couldn't implement that properly. It's not the file's fault that it cannot be opened normally. Really don't blame the file.