I have two hubs in two different rooms.  The "A" hub has a half-dozen different
machines, including the sun3.  I just did a test, and enabled SQE on the sun3's
transceiver.  Hub "B" is disconnected from hub "A".  The throughput of file
transfers between the sun3 and other machines on the same hub has dramatically
increased.  But between any other two machines on the same hub, it's horrible.
Tons of collisions.  If I disconnect the sun3 from hub "A", everything is
normal again.

Now, I connect hub "B" to hub "A", without the sun3.  Hub "B" has the sun4, and
a freebsd/intel machine.  While hub "B" is connected to hub "A", there are
tons of collisions.  Whether between machines on hub "A", or machines on hub
"B" to "A".  Reconnecting the sun3 to hub "A" just makes things worse.
If I disconnect the sun3, and hub "B" from hub "A", all the machines on hub "A"
are happy.  Throughput is wonderful.  Introducing either the sun3 OR hub "B"
into hub "A" trashes the throughput on hub "A".  I've tested this extensively.
Even if the sun4 isn't connected to hub "B", connecting "B" to "A" trashes
"A".  Doesn't make much sense, does it...

Thanks,
-Mark