Say I have a /BigProject top-level directory containing hundreds of thousands of files. I now 'svn mv BigProject NewBigProject'. Fisheye will take many hours to index this apparently simple change.

In the Subversion log this appears as a delete and an add:

Changed paths:
D /BigProject
A /NewBigProject (from /tags:2653)

I think Fisheye is treating these as discrete operations, and trying to generate a massive changeset containing every file.