The source project of this merge request has been removed.
ERP5Type/Base.py: Store a result of getCreationDate and returns it next time.
Otherwise if there is a very long history, getCreationDate becomes slow because of append-optimized data structure of WorkflowHistoryList.
According to Rafael, it already happens in SlapOS master. In my test environment, I created an object that has 470,000 lines of history of edit_workflow and it takes more than 50 seconds to call getCreationDate.