Ubuntu and network issues

Ever installed Ubuntu and your network response went down to practically 0?
Well then welcome to the club.
Installing Ubuntu out of the box and trying to get a nice network connections seems not possible. So here some things you can do to get it to normal speed.
Do the following:

edit /etc/sysctl.conf and add:
net.ipv4.tcp_sack = 0
net.ipv4.tcp_window_scaling = 0

edit /etc/modprobe.d/aliases to remove:
alias net-pf-10 ipv6
and add:
alias net-pf-10 off
alias net-pf-10 off ipv6

if this doesn't help try to comment our everything related to ipv6 in your /etc/hosts file

another thing you could do if the problem is the DNS resolution. Edit your /etc/nsswitch.conf file .

Change the following line:

hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4

into

hosts: files dns mdns4_minimal [NOTFOUND=return] mdns

if this doesn't help try the next step and change the line into

hosts: files dns.

These things should help to speed up your network connection again.