Business Architect is slow after ldap authentication

I have set the databases in my aris business server to be accessible via ldap authentication. But now I am facing a performance problem. When I log in as the local system user, everything works fine. But when I login via ldap, the login is successful, but whenever I access a folder for the first time in the database, it will take quite some time for the system to respond. Any idea what is wrong? Thanks!