Sud­denly, after the upgrade from Snow Leop­ard to the much vaunted OSX Lion, my wire­less trans­fers over a home LAN net­work became slug­gish. It was tak­ing a few *min­utes* to trans­fer a sim­ple file.

Appar­ently I am not the only one with these issues.

I tried a few fixes gleaned from a bunch of sep­a­rate threads on the Apple forum, and off the web. Not every­thing is a smart sug­ges­tion. Here's what finally works, so hope this saves some peo­ple with sim­i­lar prob­lems the time:

[You need root access for the "sudo" bits of the fol­low­ing code to work, of course.]

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sudo bash -c "echo 'net.inet.tcp.delayed_ack=0' >> /etc/sysctl.conf"
sudo bash -c "echo 'net.inet.tcp.recvspace=40960' >> /etc/sysctl.conf"
sudo bash -c "echo 'net.inet.tcp.rfc1323=0' >> /etc/sysctl.conf"

Make sure the sin­gle quotes remain sin­gle quotes in the above code share. These new sysctl set­tings will take effect after a reboot.

Another use­ful sug­ges­tion is to dis­able the IPV6 stuff. Not needed for now. Done using:


System Preferences ->
Network ->
Airport (or your WiFi listing) ->
Advanced (button) ->
TCP/IP (tab)


Change the IPV6 to "Link — Local".