I have a client that was using a Mac OS X workstation to connect to and work out of a Windows shared folder with other workstations. They kept having strange problems with the shared folder disappearing, files were not opening or saving properly, and after some research these settings seemed to help.
I don’t remember exactly which problem these settings helped with since these notes were taken years ago, however I am sharing them for posterity. These tweaks should make Mac OS X play nicer with network shares in a mixed Windows and Mac environment:
(in Terminal, with sudo) create the file /etc/sysctl.conf
net.inet.tcp.delayed_ack=0
net.inet.tcp.mssdflt=1440
kern.ipc.maxsockbuf=500000 (omit this in Lion)
net.inet.tcp.sendspace=250000
net.inet.tcp.recvspace=250000
In terminal, make finder more network friendly and skip writing .DS_Store files:
defaults write com.Apple.desktopservices DSDontWriteNetworkStores true