While the new Xbox app first debuted as an Electron application, a popular framework for building desktop apps, it now undergoes a shift to React Native as a Universal Windows Platform (UWP) app. Microsoft appears to leverage Facebook's open-source framework via the latest Fast Ring release, switching to C++ over .NET.
While the Electron framework is widely adopted for app development, React Native provides a leaner, native experience on Windows. The upshot is decreased memory usage, cut by over 50 percent on our PCs, with significant performance enhancements as a result. The app installation size has also shrunk, from nearly 300MB down to 60MB.
The switch to React Native appears to be limited to the Windows 10 Fast Ring as of publication, likely to expand to additional users with time. If you want to try the current Xbox beta app for yourself, you need to be running the May 2019 Windows 10 update at the very least, with the app available for download here.
Microsoft appears to be reworking its Xbox beta app for PC, dropping the Electron framework for React Native, with significant performance enhancements in tow.