NT4 Workstation as a router

As the title suggests I have setup a machine with two nics to route between subnets.

I know that packet transfer through the router will be slower than a hardware router but I am getting ridiculously slow speeds.

The nics are Intel Pro 100’s running at 100 full duplex.

Throughput between machines on the same subnet is in the region of 80-90mbps, whereas throughput (IP) from one subnet to another drops to between 200kbps – 2mbps.

Any ideas, is this normal and am I expecting too much.

Many thx in advance.