We have recently added the ability to view videos through the app itself, without having to use the web viewer.
For users with a lot of videos (more than 50), or a slow internet, the syncing process is taking longer than expected and causing the app to run slowly.
We are working on several options to optimize the sync and speed this up.
The recommend work around is to use the web viewer at https://www.utrapp.org
The web viewer does not sync, so does not experience the delay.