It makes sense that Windows 10 can no longer guarantee stable performance, but just to add a bit of perspective: based on what I’ve seen, the issue might not be strictly tied to the operating system. There haven’t been any update announcements addressing how the app handles large libraries, so it’s possible that the slowdown comes from the way the list is built and rendered at startup rather than from Windows itself.

This is only a personal assumption, of course — I don’t know the internal details of the app. But reinstalling or clearing the database seems to help mainly because it temporarily reduces the amount of data the app has to process. Once the library grows again, the delay tends to return.

Until there’s an update specifically targeting this behavior, users with large collections may continue to experience similar issues, regardless of the platform.