Why users or sysadmin login is taking time
If users or sysadmin user trying to login in r12, Its taking time for login process. The problem most probably its is something to do with profile option. Please make sure the debug and diagnostics is not enable at the user level for sysadmin user or users.
and please look this note also
How to Purge WFERROR (System: Error) Workflow Items? (Doc ID 804622.1)
DBA 