You can get increase by modifiying the file sys:prefs/env-archive/sys/net/netstatck.config. Edit this file and at the bottom add those two lines, if not present, tcp_recvspace and tcp_sendspace. That would be so :

TCP_RECVSPACE=102400
TCP_SENDSPACE=102400

On my 2 computers, pegasos 2 and powermac mdd I have increased the values as indicated and on a 16 mbits connection by my provider, orange, and I reach it or overcome it to 17 mbits stable. You can try to increase these values more but when downloading big files, as chrysalis.iso for example, the rate must stay stable, near of the highest. If you obtain a high value only a few seconds and then that falls a lot then your values are too high.

Good courage.

Brumiga

> Is this a stack thing [...]?

Yes, it is.

I tried this on my Mac Mini but I can't really tell if there is any difference. Is there a reason not to put those two lines in or can I leave it there anyway?

Same result here no difference in speed.
Not a big deal,hoping for improvement in future mos versions.