Puzzling, isn't it? And I do not have time (or
knowledge) to track the things down the chain for this
slowdown.
First, Qube2 is much slower than modern x86 machines, and
only "overmuscled" CPUs can saturate 100BaseTX network back in 1999.
For example, the Tulip Ethernet chip can't transfer receive packets
into unaligned DMA buffer and kernel has to copy all RX packets
from DMA buffer to mbufs.
Second, implementation of network stack is too complicated and
we can't see which part (CPU, devices, drivers, VM, protocol layer,
checksumming, etc. etc) has bottleneck without proper benchmarks.
I agree current NetBSD/mips implementation is not so optimized
for MIPS3 CPUS, though.