Originally Posted by
S_Newton
I think I solved the issue quite succinctly. He was intending to avoid the 'slowdown' caused by selecting the XREF.
The slowdown isn't caused by including that one item in the selection set, it is caused by AutoCAD redrawing each and every line with a hidden or highlighted linetype. The same effect occurs when selecting or even mousing over a dense hatch. The hatch isn't a complex object, but the many, many lines being redrawn causes the system to hangup and sometimes crash.