Nearly all apps are sluggish for a very clear reason - the average dev is ass. It's possible to make fast apps using electron, just like it's possible to make fast apps using anything else. People complain about react too, react is fast as fuck. I can make react apps snappy as hell. It's just crappy devs.

Yea, these applications are typically not slow just because the use Electron (although it's often a contributor). But the underlying reason why they are slow is the same reason why they are using Electron: developer skill.