It seems like you have three choices at the moment for desktop development (for non .NET) that I am aware of.
* C++ and GTK or other UI framework : hard but excellent performance.
* Java and Swing UI framework : easier but less performant.
* Javascript and Electron : easy but terrible performance.
Which one will prevail?
As mentioned in comments elsewhere in the thread, there are several newer projects that are trying to fill that need for performant, cross-platform desktop app development.
* Revery (language: Reason) - https://www.outrunlabs.com/revery/
* WebView (language: C/C++/Golang) - https://github.com/zserge/webview
* Dear ImGui (bindings exist for many languages!) - https://github.com/ocornut/imgui
* Flutter (language: Dart) - https://flutter.dev/
None have really stood out yet to replace Electron, but the future seems bright.