Talk is starting high cpu load

Hello dear nextcloud-community,

since I upgraded NC on my raspi3 (Debian Buster with php7.3) from 16.08 to 17.03, I experience a high cpu-load of the processes “phpd” and “php-fpm” when I use the talk app. This always makes the Webpage unreachable (gateway timeout). Unfortunately I lack the knowledge to systematically track down the root of that problem and therefore I am looking for help at this place.

Thank you!

Is there perhaps a way to reset the whole app and the database-entries?

I reinstalled NC and wiped the database because I needed a working installation. Ouch!