Windows 7 SP1+ (Ultimate), connected to both local network Samba (latest stable versions) over Gigabit Ethernet, as well as a VPN'ed Samba share that goes out over my ISP link (1200 kbps uplink).
All of my local SMB shares get wire speed on bulk file copies in nearly both directions. (My network server is a five drive RAID6, with sustained throughput well north of 400Mbytes/sec).
I get "wire" speed (ISP's uplink) pretty much doing file copies to the share that's behind the VPN.
The problem is, while file uploads are ongoing to the slow VPN'ed share, Explorer takes a VERY LONG time to enumerate the rest of the shares, and effectively, I cannot browse them at all while the file copy is ongoing.
I'm shocked that Windows's SMB client isn't multi-threaded, or at least, Explorer isn't.
In a related matter, I am very annoyed by the long timeouts for SMB accesses. Very occasionally when the VPN's down, it takes a good 15 seconds to get through logins or to get through File Browser windows on their initial launch, leaving the user to feel like the system has "hung".
Surely there are tuning knobs and/or work-arounds for Windows's SMB stack, aside from the "stupid" solutions like spending a lot of money on symmetric 1GigE ISP connectivity.