"Network Buffer Size" option missing

How much RAM does the system have? I may have a sneaky tweak you can use.

I have 4gb of RAM and 4gb of swap.

If you run:

gksudo gedit /etc/sysctl.conf

add the below lines:

net.core.rmem_default = 524288
net.core.rmem_max = 524288
net.core.wmem_default = 524288
net.core.wmem_max = 524288
net.ipv4.tcp_wmem = 4096 87380 524288
net.ipv4.tcp_rmem = 4096 87380 524288
net.ipv4.tcp_mem = 524288 524288 524288
net.ipv4.tcp_rfc1337 = 1
net.ipv4.ip_no_pmtu_disc = 0
net.ipv4.tcp_sack = 1
net.ipv4.tcp_fack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_timestamps = 1
net.ipv4.tcp_ecn = 0
net.ipv4.route.flush = 1
vm.swappiness = 10

Save the new file and close gedit, then run:

sudo sysctl -p

To apply the setting. Should make things a little nicer

The option disapeared from the GUI but is still configurable using gconf.
To see the current value, type the following in a terminal:
 gconftool -g /apps/rhythmbox/player/network_buffer_size

To set a buffer size of 512kB, type the following:
 gconftool -s /apps/rhythmbox/player/network_buffer_size -t int 512

It solved the lagging problem I had when listening to webradios.