[otrs] new case auto assigned to supportworker/performance

Hi, I was wondering if it possible to add a new case and not assign it to anyone just add it to a folder? If I add a new case without assigning the case to anyone then the case is automaticly assigned to the one that adds it. We are also experiencing slow performance on the new version of otrs and I was wondering if it is possible to tune it or something? Best regards Stian antonsen