Your problem is very normal and i think julian's suggestion is your best choice. When temporary tablespace is created with TEMPORARY type, the space will not be released until the instance is shutdown. If it is created with PERMANENT type, then SMON will do the cleanup. However, if there are large number of sort segments in your temporary tablepace, SMON may take more time to do the housekeep and your perfermance maybe affected. So the best choice is create locally managed temporary tablespace which benifits of faster cleanup and reduces contention CPU usage by SMON.