After Upgrade to 20 php-fpm causes high cpu load


after upgrading from 19 to the newest 20 (with nginx and PHP 7.3) and moving some files from another NC instance (with filescan --all) I have now the problem that the webpage of NC is really slow and the php-fpm threads will use about 25 % of the cpus for some seconds every 20 seconds or so.
What can I do?

There are a few similar topics with speed problems and some suggestions what you can do and look for. It depends also how you installed it, what you configured, so to help you we probably need more information:

You probably have the Collabora problem. Try to install all possible updates. You can also deactivate Collabora first and see if your interface becomes snappy again.

sudo snap run nextcloud.occ app:disable richdocuments && sudo snap run nextcloud.occ app:disable richdocumentscore