Performance issue with elaborate partition definition

Has anyone noticed a dramatic performance issue when a complex partition strategy is defined against an Oracle table? I am running PowerDesigner 16.5. I have a few tables that have monthly (12 months for 3 years right now) partitions and system code (9 systems) subpartitions. When I open the property window for these tables, it takes 2 or 3 minutes to respond. And clicking among the tabs in the property window also takes 2 to 3 minutes to respond. All other tables with more simplified partition strategy all open normally.