The send and receive socket buffer space has nothing to do with forwarding performance. This will only affect connections from and to the box itself.
but don't routed packets go to and from the box itself? My download speeds on my mythtv/ubuntu system jumped from 1.5Mb/s to 12Mb/s after increasing those on my firewall.
I think the bigger problem are the PCMCIA nics. PCMCIA is a slow bus comparable to ISA and most PCMCIA cards are evil old clones of already terrible MAC chips. Also check the duplex mode -- autonegotiation can fail with older cards.
I tend to agree that the problem is likely here. Laptops tend to not have superfast bus speeds. I also wonder if he actually meant that capital B. 500KB isn't too shabby (what's that 4Mb?) while 500Kb isn't so good. If he's actually pushing 4Mb through his laptops crappy old pcmcia that may be as good as it gets. --Bryan
