General: Stopped roaming NPC's take far too long to resume moving
This goes for every moving guard, merchant, quest giver. If you talk to them, they will stop, but they take far too long to continue moving.
I don't remember actual timings back in retail wrath, but I definitely remember that they took far less time to continue moving. This is especially true for the moving merchants, because I vividly remember how pissed off they made me when they would move while I was still checking what they were selling.