Thanks Dan; not real problems as such, it just seems to be rather slow at coping with updates to the files - if you, say, add a 200MB file or delete a few hundred files, it will become rather slow for a while (half a minute maybe? Maybe less?) while it catches up. It's not usually an issue, but these things tend to happen near market open and close when a load of files are read & updated, so the issue just compounds itself.
We could of course not use DFS anymore, but it's so easy and convenient...