Standard AutoCAD is a geometric drafting tool. If you draw a circle and copy it, it is just a circle. AutoCAD Electrical, however, is a schematic design tool. When a user inserts a symbol like wd-m.dwg into a drawing, the software treats it as a "smart" object.
Depending on your drafting standard, the file might behave differently: wd-m.dwg
If you have a massive control panel (e.g., 500+ terminals and 100 relays), wd-m.dwg can become sluggish. Standard AutoCAD is a geometric drafting tool