That plus the new React diff viewer in beta. The old one seemed to be a simpler Web Component inside a Rails turbo frame.
I've tested the beta one and like most SPAs it doesn't scale well to large amounts of data (large numbers of files / line counts). You can feel the DOM slowing down even on a high end macbook. It even blanked out the page a couple times, another common issue when browsers are overloaded. So I switched back to the old one.