optimal file count per directory

[SunGlare]

I'm rendering my motion shots in to separate frames, times 4 passes.

 

I use NTFS, with 4kb cluster.

 

What is the optimal file count per one directory?

 

How Path

(eq.C:\Program Files\Autodesk\3dsMax8\RenderOutput\Final Take 04 PoolSweep\two)

affects file system performance?

 

C:\Shot1\Comp - would be faster?

 

Is there any edge number that shouldn't be crossed, I've noticed that over 1000 files, I have to wait to populate list of files.

 

Thanks.