Slow file share with XP and 2000 clients

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We have 9 servers with approx. 4000 XP clients connecting to them. Once the
file size hits around 20,000 files browsing to the share folder then takes
about 30 seconds to a minute. I've scoured MS's site and found kB829700 and
another poster on this board that has seen the same thing with no responses.
I've also seen that other people that have posted in other online forums are
having the same issue. Unfortunately no one has yet to state a fix. One
person's theory is that the client computer is searching all folders before
it shows the base directory. I would tend to agree with this since it really
does seem that the more files and directories that exist, the longer it takes
to bring up. Does anyone have any suggestions or thoughts on this issue?
It's becoming a pretty big problem here...
.