THanks
all I can say is that my database has a problem (and it seems to be related to oc_filecache) and is causing problem wiht long sql queries since a long time - see link.
I setup a fresh nextcloud instance with new database and a copy of my files and this instance didn’t show this slow responsiveness anymore. But my talk history is gone and also from other apps… so this is where the question came from
What I did now is importated a full backup of the SQL Table and cleared the oc_filecache oc_filecache_extend, delete the whole preview folder and run
file:scan --all
files:scan-app-data
and start generating the previews again
So far it looks like the inital problem is gone
talk chat are still available but it seems that talk is using (hash) references to oc_filecache as files shared in talk are no more shown (I guess)
Same I see for other apps like Deck, although I could find a oc_deck_attachment
The information about shared folders is also gone/not working
but for me just running an instance for my family this is OK and will simply add the shared folders by hand again…
Or maybe someone has a better idea - thx