Hi,
I have a couple of ideas on why there is a performace problem here.
Assume that the USB interface is capable of 480 Mbit/s.

1. The file system implementation would be one bottle neck.
Think about it, the USB is connected to the VIA chipset and from there the data is transported in to local memory. The cpu needs handle this and if you use the network it needs to pipe it through to a network hardware. Lots of bottle necks.

2. The main bottleneck would probably be the CPU when transfering lots of data. More memory wouldn't hurt either to have bigger buffers for handling the idle when transfering smaller files.

Anyone checked the load on the cpu when transfering much data?

/P