Hello,
To avoid this problem you can try to put lower value at option "Search Radius" or to blacklist zones where WRobot cannot found path to go.
The problem is that gatherer task select the nearest gameobject by path distance (and not by fly distance), to get path distance he generate path for all gameobject found in search radius and not blacklisted, and when WRobot cannot generate path he take long time to load meshes/search (this take time and increment ram usage, I have already try to found solution but if I put lower limit, some paths was not generated correctly).
To resolve problem with http://www.wowhead.com/quest=25136/galgars-cactus-apple-surprise you can add to your blacklisted zones:
<Blackspot X="-317.307373" Y="-4437.53027" Z="57.3852348" Radius="10" />
<Blackspot X="-360" Y="-4337" Z="58" Radius="10" />