ZapFast

Or do you mean electron/tauri programs opening in <1 second, using less than 200 MB of RAM? Are your standards that low? In addition to have written several non-trivial tauri programs myself, VS Code for example hits this mark easily.

I'd expect a semi-competently native chat client to be several orders of magnitudes more slim than Discord, Slack or Teams. The report numbers are barely better than Teams which at Time of writing is using 244 MB of RAM for me, launching in ~3 seconds.