Had a real problem with my wifi after moving to Ubuntu from win -> my download speed was dead slow with ~2Mb/s. Tried various things including this this and finally this. The last one did the trick. It was Avahi which spoiled everything. The thing that led me to Avahi was this irritating message popping out each time I connected:
Having this changed
_AVAHI_DAEMON_DETECT_LOCAL=1
to
AVAHI_DAEMON_DETECT_LOCAL=0
in /etc/default/avahi-daemon_
Got me up to 22Mb/s after reboot. We’ll see if I could squeeze more from my cheap router flashing it with some different firmware, but for now I’m quite happy to gain a 10x speed improvement 🙂