We are working in Creo M90 + WindChill 10.2 m020
When I add to workspace an assembly that contain elements of a family tables, the system download all instances and not only those are used in assembly.
In this way I have often a lot of entity in my workspace not necessary and that make my system uselessly slow.
There is a preference set in the download section that will limit family table downloads to the instance and the generic. It may require the FT be read-only to get the limited download.
We have all hardware FTs in the Parts Library and only 2 people have RW access to the libraries. Normal CAD users see all of these parts are read-only.