Android app takes minutes to update it's view in a large folder

I have a folder with a couple thousand images inside and the Android app takes about a minute when updating the view inside.
It updates the view when the folder is opened, when the sorting is changed, and when returning to the folder from a file preview.
The update is blocking, so after a while Android will say “this app seems unresponsive”, sometimes more than once, but it just takes a very long time to be responsive again.

This issue doesn’t exist in the web view, also not in Android browsere. Everything is fine there and takes only seconds to navigate and sort.

Because of this, i can’t imagine that it’s related to my nextcloud instance in any way, it has to be an issue with the app, right?