#0 - Nov. 23, 2006, 12:15 a.m.
This data will be delivered at a very slow rate in order to reduce noticeable affects on the performance of your PC. By default, the background downloader will launch after game exit, and will stop upon game re-launch. However, you may wish to take advantage of one of the other background download options.
For more information, read the Background Download FAQ, found here: http://forums.worldofwarcraft.com/thread.html?topicId=48524887&sid=1