To begin with; In case your application is running several Scheduled events or Microflow timers, check wether the intervals are not overlapping eachother and even more important, the scheduled events or timers should not delay the following tasks.
Further more, check if your application has microflows with For-loops that run database transactions. Loops with database transactions like retrieves from DB, commit or delete are performance killers when used in loops.
at last, check wether your application is running CRUD transactions on Indexed entity attributes, or search running with ends-with and conains functions. If you have these, replace them with ‘starts-with’ and ‘equals’.
Hope this helps you getting your app back into performing better,
Close all Studio Pro instances and check in task manager for studiopro processes that have been left behind. I have these a lot. Memory management is better with 9.18.x but also with 9.18.3 I have orphaned studiopro processes, especially when working with pages a lot. Sometimes these go away if you also close all Chrome tabs. If not, you can kill these but make sure there are no Studio Pro instances open!
Do the issues also occur in the latest MTS 9.12.8?
If so, would it be an option to upgrade to the latest LTS 9.18.3?
A lot has happened since 9.12.1.