Complex workflows involving "Data Collector" workflow controls may in very specific circumstances seriously degrade overall system performance.
Installing the hotfix will bring a new option "Merge workflow parameters from all collected data" to the "Data Collector" workflow control (which will be standard available as of Automation Engine 20.0).
When switched off, and after carefully checking if this has no unexpected effects, this may considerably improve system performance.
Complex workflows involving one or more "Data Collector" workflow controls may in very specific circumstances, typically when many files travel the workflow and/or lots of workflow parameters come into play, seriously degrade overall system performance.
Possible effect could be that tasks for no clear reason don't seem to start anymore, and it looks as if the system is hanging. In reality however, this can be a sign of the workflow engine getting overloaded while it calculates the effect of workflow parameter changes in the different paths up to the (multiple) data collector(s). Typically, the system gets through, but it first seems blocked for (possibly quite) some time.