I had this problem since I installed Maverick on MacPro 2x 2.4 quad-core xeon with 28 Gb of RAM. I am now on 9.2.4 and the problem is even worst!
Are you still having the same problems?
I saw 2 solutions. Will they work in my case?
I use dropbox and I have a Sonnet 5-bay Fusion ext box with 3 drives in it as well as 4 internal drives in the Mac Pro. So I have 7 drives in total.
How to disable the dropbox appli/helper?
Was is the effect of commenting the line in auto_master?
#/net -hosts -nobrowse,hidefromfinder,nosuid