With a 10 Mbps interface? Exactly the same speed. With a 100 Mbps interface? The upper bound is higher, assuming your peripheral bus provides enough bandwidth, but the same basic rules re: actual throughput still apply. I don't think any classic Amiga system, regardless of processor, can process data quickly enough for a 1 Gbps interface. A G-Rex on a Blizzard PPC might reach half that if the system was doing nothing but pushing raw Ethernet frames. Anything faster than that is obviously out of the question unless you build a custom interface with a very, very, very large buffer.
