I use Realm in production in several applications developed with react native. Multiple users complained that the app slows down significantly when they use it for several hours offline. The app is intended for offline-first use. Weirdly, when they go online, the app functions normally.

We use the latest realm-js version with react native, realm sync and react-native-navigation. I was able to reproduce the bug and realm is definitely the issue. I can give access to private repository if a contributor is interested.