Files in vault - to subfolder, or not to subfolder

Hi all,

We are in the process of implementing Enterprise PDM, and I am considering the issue of where to put all our legacy files.  We will be bringing in 10- to 20-thousand files.  It has been suggested to me by our VAR that we should aim for no more than 10k files per folder. 

Currently all the files reside in a single folder on the network (not in the vault) with about 20k files.  Sometimes there is a few seconds' lag in opening this folder, depending on the exact workstation used.

However, having pinged our company's user base on the issue, it seems they are quite concerned that any kind of subfolder structure would be an unacceptable nuisance.

So, my question is, is there a noticeable performance benefit to splitting files into subfolders?  i.e. does the benefit outweigh the extra time required for one more double click?

Would this require us to monkey around with reference file location settings, or will SW/ePDM be able to find a given file regardless of being in some subfolder?

We are on version 2010, with workstations running XP 32, XP 64, and Win7 64.  We also have a vault replicated across two sites (Milwaukee, WI and Rockland, ME).

Thanks in advance for any suggestions or advice.

SolidworksSolidworks Pdm enterprise Pdm