Atom takes longer to start up than text editors like Vim and Sublime Text because of the dynamic architecture of the app. The majority of our code is written in JavaScript as opposed to C or C++, which is important for Atom’s extensibility, but makes it more challenging to ensure that the app starts quickly.
Yet Microsoft's VSCode, which is also Electron based, is much faster than Atom. Electron obviously slows it down, but Atom's refusal to admit their performance issues for so long are also to blame