If you have a job (either as a freelancer or professional) you certainly should be able to afford to pay for a $70 license, if you cannot then maybe your problem is your salary. If you are a student, ask your parents for it. I have given away at least 8 single-user licenses to friends and fellow co-workers who had your mentality, and they are now happy SublimeText users.
The problem that I see with Atom IS NOT in the startup speed, which is something that many people complain about, obviously you can just open the program once in the morning and leave it running during the day... Oh wait! You cannot! Because the program is running on top of a full-feature web browser (and one of the most heavy ones) which means that during the day it will consume a significant amount of RAM. Do you want to listen to music while you write code? You got it! Atom will turn up your computer's fan for you so you can listen to the peaceful sound of air blowing at your CPU because the full-featured browser behind it is doing some crazy shit in the background.
I don't even care about the loading screen when you are opening large files, the major problem that I notice is keystroke lag, after the first hour or so I start to notice some lag between the input from my keyboard and the actual visual in the editor [1].
Some time ago I thought that GitHub would get tired about the criticism of their beloved project and deprecate it, but then they converted their Git client [2] into an Electron app. They are really invested into that technology. If I were one of their engineers I wouldn't mind to take a C++/Qt project alone just to be able to provide a resource-friendly program that people will love for its performance (as we do for SublimeText) more than for its plugin ecosystem and "beautiful" themes.
You know, the first thing that I do every time I need to install SublimeText into a new computer is to disable some settings, not because they are going to make the editor faster but because I really don't need them. But with Atom, I really-REALLY need to disable many built-in plugins because they are either tracking me or because they are genuinely slowing down the program (the GIT integration, for example). I configure SublimeText to my needs because I want to, I configure Atom to my needs because I need to.
[1] I am sure there will be someone in the replies saying that they don't notice any lag, they will even include the amount of RAM in their computer as if it was relevant (no, it is not, it's a code editor, it should be fast). The fact that it runs well in your computer doesn't means the problems don't exist.
