Why is the Windows 7 network drive access/transfer so extremely slow using Boot Camp 4.0?

I experience extremely slow network drive access and transfertime in Windows 7 using a MacBook Pro Late 2011 and boot camp 4.0.

I read in threads like the one below, that it might be a bug in the network drivers as mentioned in this thread:

http://social.technet.microsoft.com/Forums/eu/w7itproperf/thread/4537c7b6-9761-4 1c5-8b47-0ecb831c8575

Is it still a problem in Boot Camp 4.0? Which drivers might resolve the problem?

Kind regards

MacUser-SRN