Because that usually isn't the reason. I tend not to work on files in DropBox. Rather, I use it for offline storage and to ensure that I can access things from the MBA when I am on the road.

The desktop app seems to spend forever indexing and synchronising at unpredictable times, to the point where I pause it and then resume before going to bed.

I've tried linking and unlinking, but not yet uninstalling and reinstalling.

Right now it seems to be behaving a bit better.