Slow access to mapped network drives on 1st access

It is taking 15 - 30 seconds or longer to open a view of
a mapped network in windows explorer. Once the view has
been opened it will function normally for a period of
time. If not accessed or if the machine is rebooted it
then takes a long time for the view to open. I've
installed SP1a and applied the fix in article 814952.
Need suggestions.