I think that’s just the shader caching being rendered isn’t it? I know totk has some caching that can be pre downloaded but I believe it still is cached when you are running the game. I think it stabilizes after a bit but I had trouble getting ryujinx and yuzu working so I opted for the cemu (wii I) route.
Rebel galaxy is awesome. Broadside combat with a smile. I hope you’re enjoying it.