If after a massive import you receive the notification "PaperOffice performance is currently being severely limited by the mass processing process"

and it doesn't disappear after a while although apparently all documents have been imported correctly, please do a database check.

For this go to "Documents in processing" by clicking on the hourglass icon in the lower right corner.

If you still see documents in process click on "Cancel everything"

Close the window "Documents in processing" and enter settings by clicking on the gear icon in the upper right corner

Go to "Database, backup and export" and click on Complete database maintenance manually now, wait for the process to finish and restart PaperOffice.