Yeah, they are a pita for me. It's become part of my routine login process to go in and kill them, or not everything will rez. I always have at least two, sometimes four going...not sure what determines how many
You do need them for search. I've had to search after stopping them, and eventually one will run again to do that...I might have to hit the search button a couple of times and it takes a long time to get it started, but it does eventually complete the task.
Also, as soon as my avi starts jerking or becomes uncontrollable in walking...that's the first thing I check, to see if one is running, and 9 times out of 10, it is. I stop the process and my avi smoothes out again. I hate them!!!