I've just finished some ttcp runs. with large bufefrs and large window
I'm using large-ish socketb-buffer  and window sizes:

  ttcp-t: buflen=16384, nbuf=40960, align=16384/0, port=5001, sockbufsize=65535  
and testing send and receives, pairwise  between all three of:

Pentium 133, Endeavour motherboard, NetBSD-1.3H, de500
    Pentium 133, Endeavour motherboard, NetbSD-current, 3c905B
    Pentium 200-MMX, Dell(?) , Linux 2.2.1, 3c905B

(1.3H is an old -current from late Novembner, but I cant upgrade till
i finish getting a batch of numbers).
 
The linux box can send at 75 Mbit/sec. Both netbsd boxes can send and
receive at just over 60 Mbit/sec.

So it looks like the 905B throughput is at least comparable to a
de21140-based NIC.

(I pulled a 3c595 to put in the 905B; that box was getting roughly 50
Mbit/sec; i can put it backin and rerun the tests if anyone really
cares.)