When a user changes a field and/or an individual import job is loaded via the data importer every record fires an event, some are unnecessary (al_fired_event, arg_job, arg_job_task). I believe only the actual data coordination service (DCS) required individual fields should fire an event (contact name, cost center, user id, etc.). Currently the event service is triggered off of the version field whereas I believe it should be triggered off of the required DCS individual fields.
This causes useless records (in some cases very large amount of records) to be stored in the al_fired_event table, which ultimately can cause performance issues such as the DCS stalling. I saw this occur when the al_fired_event table reached 3 million records. At the bare minimum, I believe code/fix/patch should be added to APM to purge completed al_fired_event records as well as any underlying tables. If the purge code was added then I believe this non-DCS individual field changes would not cause such a performance hit.