Atom is slowest editor I've ever used. Visual Studio would have to do pretty badly to reach that level. Atom is good in other ways. It's very extensible. But my cursor actually had noticeable lag.

Erm, I hate to break it to you, but VSCode and Atom are both Electron-based, so they're not exactly light on resources either... If you are going to have a whole browser engine running, I guess it makes sense to at least make a full-blown IDE out of it rather than a simpler editor (or a glorified chat app like Slack)