I wonder how much of this is just a psychological effect from knowing it's Electron beforehand.

Sometimes I think I can almost perceive a little bit of slowness compared to e.g. Sublime—but then I lose sight of it.

Certainly in comparison to any similarly fully-featured IDE I've used its feel is notably quicker.

Its more the electron tradeoff. We have picked slightly slower software if it means more software at a cheaper price which works on more platforms and has more features.

Vim and sublime still exists and yet people flock to VS code because they would rather get a more powerful laptop to run an electron app.