Comment by ssl-3

The only USB thing it has is a NIC. But given the speed of my ISP I could get around that by using VLANs, I guess.

I mean: There's not much to it. LAN port, WAN port, MicroSD storage, and a (completely optional and of dubious merit) hardware RTC that sits on the GPIO header. I'm using the bog-standard Pi Foundation plastic case.

It runs OpenWRT, which itself is very light-weight -- it's more-or-less just enough Linux to set up routing functions using a GUI, and it's meant to be able to fit in the tiny little bit of flash that consumer router hardware comes with.

IIRC, the status at the time when I put it together was that it could route packets and perform traffic shaping at ~1Gbps even with a USB NIC. It certainly did just fine when I had a 400Mbps pipe.