Just flat-out more efficient code may have a lot to do with it (I have not deeply explored the codebase for either project). However, I suspect that the larger

Just flat-out more efficient code may have a lot to do with it (I have not deeply explored the codebase for either project). However, I suspect that the larger reason is that Atom ships with a ton of plugins enabled by default, whereas VS Code ships relatively lean. If you look the settings in Atom, it tells you specifically how many milliseconds each plugin adds to startup time. They REALLY add up. Install even more plugins to customize your editor, and it rapidly enters IDE bloat territory. All that being said, VS Code recently launched a plugin marketplace of its own. I've installed Vim emulation and a couple of others, and really haven't noticed any increase in startup time.