I am designing a tooltip for nautilus, and I noticed that there is a Bug 147642 about tooltips. I take windows explorer as example. In windows when mouse move over a big directory, it would show "More than ... ",
Until windows tooltip finally tells how much disk space this directory used....
I try to avoid too much deep counting by caching the results as metadata in directories, and invalidate the metadata by recompute deep counting at proper time. The proper time maybe when a NautilusFile is added, removed or changed.