That is actually not a bad amount, the native Telegram macOS client hovers around the same. WhatsApp Web (also built on Electron) consumes a staggering 300-500mb.
Electron is several things which HN guidelines probably won't allow me to describe here. I avoid it whenever I can.
You may even embed some web-engine. It doesn't have to involve obscene amounts of megabytes and the selling of your soul to the Google monster.
Some bugs here and there but paired with a tool to layout UIs (like wxFormBuilder), you can get a lot done.